The proportion of women who experience a depressive state after delivery differs between primiparas and multiparas, so it is important to clarify the different factors related to depression between the two groups. In this study, we confirmed the differences in depressive states, the perinatal period, and social support between primiparas and multiparas, and clarified their characteristics. Data were extracted from a prospective cohort questionnaire survey conducted on pregnant women in Japan that included sociodemographic questions, the Edinburgh Postnatal Depression Scale, and the Japanese version of the Social Support Questionnaire. We carried out the chi-square test, Student's t-test, and analysis of covariance to compare responses between primiparas and multiparas. A total of 1138 primiparas and 380 multiparas provided valid responses. We found that primiparas had higher rates of experiencing maternity blues and postpartum depression than multiparas. We also found that primiparas had higher anxiety scores than multiparas. Primiparas with postpartum depression perceived a lower number of persons available to provide social support than primiparas without postpartum depression. These findings suggest that it is important to provide pregnant women, especially for primiparas, with information that allows them to increase the number of people who can provide them with support.