This study provides the first evidence on a variety of life course outcomes of birth weight in Japan by employing new datasets covering the middle and older generations. We have several interesting observations. First, low birth weight is significantly associated with adverse　outcomes in early life including school performance and self-rated health. Second, no negative effect of low birth weight is found on educational attainment or primary job status. Third, health outcomes due to low birth weight at older ages are not negatively affected except for difficulty in mobility and higher risk of diagnosis with hypertension or diabetes. Overall, our findings suggest that the negative effect of lower birth weight seems to fade out over the life course.