Purpose : The purpose of the present study was to clarify factors related to mothers' perceptions of fathers' support for 18-month-old infants. Methods : The subjects were 323 mothers with 18-month-old infants who were undergoing a scheduled health check in A City, Hokkaido. Data were collected using an anonymous, self-administered questionnaire. The questionnaire focused on the mother's perceptions of the father's support according to the mother's background, the father's working hours, the time the father returns home from work, the number of hours the father works per week, the father's participation in child rearing, and the mother's happiness with child care. Data from 161 (49.8%) valid responses were subjected to analysis using the Mann-Whitney U test. Results : Most mothers confirmed receiving emotional support from the father. Significant relationships with the mothers' perceptions of fathers' support for 18-month-old infants were found for "mother's occupation," "birth order," "best person in child-rearing support," "the time the father returns home from work," "the father's participation in child rearing," and "mothers' happiness with child care." Discussion : This study showed that mothers' recognition of their expectations of the fathers' participation in child rearing affected their perceptions of the fathers' support. Furthermore, these findings emphasize the important influence of mothers' happiness with child care on their parenting and family.