| S.C. Building Service Co., Ltd. | Facility management of buildings (Cleaning, equipment maintenance and security) | Living Related & Real Estate |
| S.C. Cement Co., Ltd. | Sales of cement, ready-mixed concrete and concrete products | Living Related & Real Estate |
| SC-ABeam Automotive Consulting | Automotive industry focused consulting | Transportation & Construction Systems |
| SC Digital Media K.K. | Operation management and investment activities in digital media | Media & Digital |
| SC Foods Co., Ltd. | Developmental import and sale of foods, meat, beverages, grains, fats, sugars, etc. | Living Related & Real Estate |
| SC Machinary & Service Co., Ltd. | Sales of various kinds of machines and equipment | Transportation & Construction Systems |
| SCSK Corporation | Software development, information processing service, communication network service, sales of package software as well as software and hardware, SI service and others, and BPO | Media & Digital |
| Sharing Design Inc. | Providing 5G-centered base station sharing services to mobile communications carriers | Media & Digital |
| Shinko Sugar Mill Co., Ltd | Raw sugar production | Living Related & Real Estate |
| SMB Kenzai Co., Ltd. | Sales of various building materials and construction work | Living Related & Real Estate |
| Solar Power Kitakyushu Corporation | Solar Power IPP | Infrastructure |
| Solar Power Minamisoma Haramachi Inc. | Solar Power IPP | Infrastructure |
| Solar Power Minamisoma Kashima Inc. | Solar Power IPP | Infrastructure |
| Solar Power Saijyo Corporation | Solar Power IPP | Infrastructure |
| Solar Power Tomakomai Corporation | Solar Power IPP | Infrastructure |
| Spring Infrastructure Capital Co., Ltd | Fund management of infrastructure funds | Infrastructure |
| Sumisho Administration Services Co., Ltd. | Personnel and general affairs services | Corporate Group |
| Sumisho Aero-Systems Corporation | Sale of aerospace equipment | Transportation & Construction Systems |
| SUMISHO AIRBAG SYSTEMS CO.,LTD | Manufacture and sale of side curtain airbag cushions for automobiles | Transportation & Construction Systems |
| Sumisho Building Management Co., Ltd. | Operation, management, planning and consulting service for office buildings, construction work, management and contracting for buildings and equipment including electric systems, and tenant brokerage | Living Related & Real Estate |
| Sumisho Global Logistics Co., Ltd.(SGL) | Global Logistics Service Provider | Infrastructure |
| Sumisho Insurance Corporation | Insurance agency | Infrastructure |
| Sumisho Interior International Inc. | Interior design, construction and interior product procurement, import, export, sales of furniture and carpet, and industrial materials | Living Related & Real Estate |
| Sumisho Marine Co., Ltd. | Newbuilding, Second-hand, Chartering, Arrangement of ship finance, Marine equipment business, Ship management support | Transportation & Construction Systems |
| Sumisho Materials Corporation | Trading of precious metals and other products | Mineral Resources, Energy, Chemical & Electronics |
| Sumisho Metalex Corporation | Sale of nonferrous metal products, Electronic part material
and Battery material | Mineral Resources, Energy, Chemical & Electronics |
| Sumisho Montblanc Co., Ltd. | Planning, production and sales of white coats, service industry uniforms, work uniforms and related clothing products, as well as production and sale of linen materials | Living Related & Real Estate |
| Sumisho Realty Management Co., Ltd. | Investment management business, investment advisory and agency business, Type II financial instruments business, and building lots and buildings business | Living Related & Real Estate |
| Sumisho Tatemono Co., Ltd | Sales, brokerage, leasing and management of real estate | Living Related & Real Estate |
| Sumisho Urban Development Co., Ltd. | Planning, development, management, and operation of shopping centers | Living Related & Real Estate |
| Sumisho Well Support Co., Ltd. | Administrative services | Corporate Group |
| Sumitomo Corporation Global Metals Co., Ltd. | Sales of metal products & metals and services within Japan, import and export, trilateral trade, and domestic and international business investment | Metal Products |
| Sumitomo Corporation Global Research Co. Ltd. | Think tank within the Sumitomo Corporation Group which performs surveys and analyses of domestic and overseas political administrations, economies, and industry trends | Corporate Group |
| Sumitomo Corporation Power & Mobility Co., Ltd. | Trade in automobiles, railcars, etc., and electric power project facilities, development and implementation of overseas electric power infrastructure and railway infrastructure, new business development in the mobility field | Transportation & Construction Systems |
| Sumitomo Mitsui Auto Service Company , Limited | Leasing of motor vehicles | Transportation & Construction Systems |
| Sumitomo Mitsui Finance and Leasing Co., Ltd. | Leasing | Transportation & Construction Systems |
| Sumitomo Precision Products, Co. | Manufacture and sale of aircraft components and heat exchangers | Transportation & Construction Systems |
| Sumitomo Shoji Chemicals Co., Ltd. | Sale and trade of plastics, organic chemicals, inorganic/ fine chemicals and electronic materials | Mineral Resources, Energy, Chemical & Electronics |
| Sumitomo Shoji Financial Management Co., Ltd. | Financial services such as cash management, trade settlement, back-office of financial and commodity business and accounting services to Sumitomo Corporation and its subsidiaries | Corporate Group |
| Sumitomo Shoji Machinex Co., Ltd. | Sale of machinery and equipment | Infrastructure |
| Sumitronics Corporation | Electronics Manufacturing Service | Mineral Resources, Energy, Chemical & Electronics |
| Summit, Inc. | Supermarket chain | Living Related & Real Estate |
| Summit Agri-Business Corporation | Manufacture and sale of fertilizers and agriculture-related materials | Mineral Resources, Energy, Chemical & Electronics |
| Summit Agro International, Ltd. | Development and distribution of crop protection products, household insecticides and pet care products | Mineral Resources, Energy, Chemical & Electronics |
| Summit Air Service Corporation | Travel agency | Infrastructure |
| Summit-Benichu Coil Center Co., Ltd. | Purchase, shearing, slitting, and sale of steel sheets | Metal Products |
| Summit Cosmetics Corporation | Manufacturing, Import and Export Sales, and Research & Development for Cosmetic Product and its ingredient | Mineral Resources, Energy, Chemical & Electronics |
| Summit CRM, Ltd. | Trading of carbon-related materials (coke, etc), refractories and ferrous raw materials | Mineral Resources, Energy, Chemical & Electronics |
| Summit Energy Corporation | Planning, development and operation of domestic retailing of electric power, domestic business in electric power and energy field and controlling its 5 subsidiaries
・Summit Mihama Power Corporation
・Summit Onahama S Power Corporation
・Summit Myojo Power Corporation
・Summit Handa Power Corporation
・Summit Sakata Power Corporation | Infrastructure |
| Summit Energy Development Co., Ltd. | Advisory services for exploation, development and production of natural gas and other resources and the related business | Mineral Resources, Energy, Chemical & Electronics |
| Summit Global Power Ltd. | Development, asset management and technical support for power generation and desalination projects (This company has a branch in Abu Dhabi, United Arab Emirates) | Infrastructure |
| Summit Handa Power Corporation | Biomass-fired power generation | Infrastructure |
| Summit Mihama Power Corporation | Power and steam supply | Infrastructure |
| Summit Myojo Power Corporation | Power generation | Infrastructure |
| Summit Oil Mill Co., Ltd. | Manufacture and sales of vegetable oil, and contract manufacturing, filling and packaging | Living Related & Real Estate |
| Summit Onahama S Power Corporation | Power and steam supply | Infrastructure |
| Summit Pharmaceuticals International Corporation | Drug discovery services, pharmaceutical development and supply of active pharmaceutical ingredients, intermediates and formulations | Mineral Resources, Energy, Chemical & Electronics |
| Summit Sakata Power Corporation | Biomass-fired power generation | Infrastructure |
| Summit Steel Co., Ltd. | Shearing, slitting, and sale of steel sheets | Metal Products |
| Summit Wind Power Corporation | Wind Power IPP | Infrastructure |
