The objective was to examine the association between age at menarche and all-cause mortality. A population-based prospective study involving 55,128 Japanese women aged 40-79 years in 1988-1990 and followed up to December 2006 was used. A total of 6,967 deaths occurred during the follow-up. Hazard ratios (HR) and 95% confidence intervals (CI) adjusted for age, smoking and drinking status, exercise, sleeping hours, parity, menopausal status, and body mass index at baseline were calculated by Cox proportional hazards model. The HRs (95% CI) of all-cause mortality were 1.16 (1.01-1.32), 1.01 (0.92-1.11), 1.00, 0.97 (0.90-1.05), 0.98 (0.91-1.05), 0.92 (0.84-1.01), and 1.05 (0.96-1.14) for women with menarche aged 9-12, 13, 14 (referent), 15, 16, 17, 18-20 years, respectively, indicating an inverse J-shaped association (P for quadratic trend <.01). Moreover, women with menarche aged ≤12 years have a significantly high risk of all-cause mortality compared with those with menarche aged ≥13 years (HR 1.17, 95% CI 1.03-1.33). Comparing between women with menarche aged ≤13 years and ≥14 years, those with earlier age at menarche had borderline significantly high risk of all-cause mortality in both comparisons (HR 1.07, 95% CI 0.99-1.15, P = .082). Japanese women with early age at menarche of ≤12 years were associated with increased risk of all-cause mortality and those with late age at menarche of ≥18 years also had a slightly higher mortality risk. These associations were independent of lifestyle, anthropometric, and reproductive factors.