Psychosocial factors related to the career patterns of exercise behavior in the middle-aged were assessed by qualitative research design and a semi-structured interview method. First, as a screening survey, 166 females and males completed a questionnaire that included scales about their career patterns of exercise behavior after school education, and their psychosocial factors were categorized into one of the following career patterns: maintenance, sedentary, adoption, dropout, resumption, or occasional. Secondly, of the initial sample, eighteen interviewees were selected for further in-depth interview research, in order to investigate typical exercise career patterns. Psychosocial factors af fecting career patterns of exercise in the middle-aged revealed in this study were as follows: (1) factors of perceived unhealthy states, social support, and life events influenced the adoption of, or dropout from, exercise; (2) cognitive factors affecting subjective evaluation of meaningful experiences, perceived contingency, and motivational autonomy influenced the dropout from, and maintenance of, exercise. These results suggest that life-style and perceived well-being in middle age to later life are relevant for diversification of career patterns of exercise behavior as sedentary, sedentary to adoption, adoption to maintenance, or maintenance to dropout.