•We examined the association between personality and alcohol use during pregnancy.•Higher extraversion was associated with alcohol use in early and middle pregnancy.•Higher psychoticism was associated with continued use into middle pregnancy.•Neuroticism was not associated with alcohol use during pregnancy.•Lower lie was associated with alcohol use in early, but not in middle pregnancy. Studies on associations between maternal personality and alcohol use have examined only one time point during pregnancy in Western countries. We aimed to examine the association between maternal personality and alcohol use in early and middle pregnancy in Japan. We analyzed data from 17,144 pregnant women in Japan who participated in the Tohoku Medical Megabank Project Birth and Three-Generation Cohort Study from 2013 to 2017. Personality was assessed using the short-form Eysenck Personality Questionnaire-Revised. Women were dichotomized as current drinkers or non-drinkers in both early and middle pregnancy. Odds ratios (ORs) and 95% confidence intervals (CIs) for alcohol use in early and middle pregnancy and continued alcohol use between early and middle pregnancy were calculated for 1 standard deviation increase in each personality scale, adjusted for age, as well as education, work status, fertility treatment, and parity. Higher extraversion scores were associated with alcohol use in early (OR, 1.16; 95% CI, 1.12–1.20) and middle pregnancy (OR, 1.17; 95% CI, 1.10–1.25). Higher psychoticism scores were associated with continued alcohol use into middle pregnancy (OR, 1.07; 95% CI, 1.01–1.14) and alcohol use in middle pregnancy (OR, 1.07; 95% CI, 1.02–1.13). Neuroticism was not associated with alcohol use in early or middle pregnancy. Lower lie was associated with alcohol use in early (OR, 0.95; 95% CI, 0.91–0.98), but not in middle pregnancy. Different personality scales are associated with alcohol use at different points during pregnancy.