Despite its powerful economic status, Japanese people experience relatively low levels of life satisfaction. This paper addresses important determinants affecting Japanese people’s life evaluation, and examines life satisfaction across different age groups. Also important determinants in each age and gender group are identified. Using a representative survey of Japanese respondents (15 or older) conducted since 2006, the study finds that material well-being is the most important determinant of life satisfaction. Other factors such as marital status, affective experience, education are also significant predictors. There seems to be a downturn of life-satisfaction across life-cycle, such that individuals in late adulthood are the least satisfied with their lives. Although a gender gap exists for levels of life satisfaction at each life stage (favoring women), the declining slop is especially notable in the elderly women. We argue that follow-up studies of life satisfaction in Japan could benefit from considering social issues based on national characteristics such as relative wealth, age, and gender inequality.