[SUMMARY] Objective: To clarify through a literature review the content of social support that was an effective intervention for middle-aged men in lifestyle improvement programs, and to obtain materials for developing a program that utilizes social support to promote lifestyle improvement among middle-aged men. Methods: Using PubMed, CINAHL, PsycINFO, and the Japan Medical Abstracts Society's database, we searched the literature published between 2010 and 2019, and identified 11 studies for analysis. Social support data were extracted and analyzed qualitatively. Result: As a result of analysis, social support that was effective in lifestyle improvement programs for middle-aged men comprised “providing advice necessary for lifestyle-related disease prevention”, “providing opportunities to connect with healthcare professionals and peers working to improve lifestyle, as well as related self-management tools”, “creating friendly competitive relationships with peers working to improve lifestyle”, and “encouragement and approval of lifestyle improvement efforts”. Conclusion: The content of social support that was effective in improving the lifestyle of middle-aged men was a combination of face-to-face and non-face-to-face support provided not only by professionals, but also by other program participants, as well as mutual encouragement among the participants.