environment and children's Study (JecS) Group 22 evidence is mixed on the associations between physical activity during pregnancy and perinatal depression, and it is limited for different physical activity intensities. Data for 92,743 pregnant women from the Japan Environment and Children's Study were analyzed in this study. Psychological distress during pregnancy was assessed as moderate or severe using the Kessler Psychological Distress Scale (K6 5-12 and ≥13, respectively). Postpartum depression was assessed using the Edinburgh Postpartum Depression Scale (EPDS; cutoff score 9). Women with only light physical activity had significantly lower odds of psychological distress during pregnancy than those with no physical activity (K6 5-12: adjusted odds ratio [AOR] 0.86, 95% confidence interval [95%CI] 0.82, 0.90; K6 ≥ 13: AOR 0.64, 95%CI 0.58, 0.72). Women with a combination of light, moderate and vigorous physical activity had significantly higher odds of psychological distress during pregnancy (K6 5-12: AOR 1.32, 95%CI 1.18, 1.48; K6 ≥ 13: AOR 1.45, 95%CI 1.16, 1.81) and depression after childbirth (EPDS ≥ 9: AOR 1.42, 95%CI 1.24, 1.61). physical activity intensity should be considered when assessing psychological distress risk during pregnancy and depression risk after delivery. Future research should evaluate specific physical activity programs with optimal intensity for pregnant women to prevent and treat their psychological distress and depression.