Objectives: In the stressful contemporary society, support for mental health is socially conducted. The purpose of this study was to clarify the association between social interaction in adulthood and mental health using survey data for local residents by age group.

Methods: All participants were aged between 20 and 59 years and lived in the municipality. In questionnaire survey in 2014, as well as every three years following the survey, 948 people without missing data were analyzed. We analyzed the association between relationships with society and mental health three years later; the Index of Social Interaction Scale was used, along with stress level over the previous month. A univariate logistic regression analysis was performed, classifying participants as a whole and stratified by age in 10 year increments; age, gender, and relationship with society were explanatory variables, while mental health was an objective variable. Next, we carried out a multiple logistic regression analysis.

Results: As a result of the multiple logistic analysis, in terms of the adults as a whole, a significant association was found between the scores on the subscale of independence, interaction, and mental health. In terms of age group, similar associations in the subscale of independence of life were found between adults in their 30s and 40s. Also, in the 30s age group, a significant association was found in the area of feelings of safety, and in the 40s age group a significant association was noted in the area of interaction with others.

Conclusion: It is suggested that one’s social interaction during adulthood may be an important factor contributing to the maintenance of mental health. In particular, I think that it suggests the importance of support in the area for adults in their 30s and 40s has been established.