A steep increase in young people’s participation in eSports in Japan has demonstrated potential adverse health effects as well as impacts on their well-being. Therefore, protective guidelines are required to address this issue. Hence, a novel measurement tool was used in this study to understand the social and health effects of sports. Using an online survey (n= 1,612), factor analysis yielded a two-factor structure for the 12-item eSportsmanship scale. Analysis of covariance was used to test whether the factors of cooperative and normative eSportsmanship and time spent playing eSports were associated with well-being, physical health problems, gaming addiction tendencies, empathy, and self-positivity. Cooperative eSportsmanship was associated with favorable psychological tendencies, such as well-being, empathy, and positive affect. The findings also suggest that increasing normative eSportsmanship can inhibit physical health problems and the degree of gaming addiction. The analysis of covariance demonstrated that more time spent on eSports was significantly negatively associated with physical health problems, gaming addiction tendencies, and aggressive feelings. Future research should aim to clarify the causal relationship between these psychological tendencies and eSportsmanship and conduct a detailed analysis of whether the effects and impacts of eSportsmanship differ according to game genre.