Objectives This study aimed to analyze and clarify the role of public health nurses (PHNs) in assisting mothers who need assistance during antenatal checkups.Methods This study was conducted in core city, A. The study participants were PHNs who experienced supporting at least three mothers who required support during maternity health checkups. We interviewed the respondents about their observations, decision points, difficulties in coordination, and other aspects of support. Data were extracted from verbatim transcripts and analyzed inductively.Results Sixteen PHNs participants had an average of 9.3 years of experience. The analysis included 10 categories, 43 subcategories, and four themes. PHNs connected with mothers early depending on the mothers' wants, based on information gathered during the gestational period (theme 1). PHNs make early telephone visits to mothers based on information obtained during the gestational period. If the mother did not respond to the initial visit, the PHNs attempted to establish contact through other means.PHNs carefully observed and assessed mothers' childcare routines and mental and physical conditions (theme 2). To assess the mothers' mental health status, they were interviewed in detail using the Edinburgh postnatal depression scale. Determining the mother's condition was challenging; therefore, several PHNs conducted multiple visits and repeated the observations to achieve accurate assessments.The PHNs stayed close to their mothers and carefully supported them toward independence while assessing their progress (theme 3). PHNs established trusting relationships with mothers.PHNs served as coordinators in resolving problems and provided ongoing support in cooperation with medical institutions and related organizations (theme 4). The PHNs carefully coordinated consultations and encouraged mothers to consult psychiatrists if appropriate. Conclusion Although PHNs provided attentive care to mothers requiring assistance, difficulties arise in accurately diagnosing postpartum depression and connecting mothers to psychiatric services. Guidelines that standardize the assessment of and responses to mental health issues are required. It is necessary to organize the problems faced by mothers and develop a system of cooperation among various organizations.