The purpose of this study was to examine factors influencing college students’ self-efficacy toward pregnancy planning by gender using the health belief model (HBM). Utilizing a comparative descriptive design, a total of 819 college students were recruited. A survey was administered to gather information on health beliefs related to pregnancy planning, self-efficacy toward pregnancy planning, fertility knowledge, and general characteristics. The main variables were compared by gender. The factors influencing self-efficacy toward pregnancy planning were identified using hierarchical regression analysis. Female students (476) had lower self-efficacy toward pregnancy planning than male students (343). The significant factors influencing self-efficacy toward pregnancy planning in female students were: depression (β = −0.09, p = 0.030), fertility knowledge (β = 0.08, p = 0.025), barriers (β = −0.57, p < 0.001), and cues to action (β = 0.16, p < 0.001), whereas the corresponding factors in male students were benefits (β = 0.12, p = 0.020), barriers (β = −0.44, p < 0.001), and cues to action (β = 0.16, p = 0.001). The present study confirmed the suitability of the HBM as a conceptual framework for identifying factors influencing self-efficacy toward pregnancy planning. Based on the findings of this study, gender-based similarities and differences in factors influencing self-efficacy should be considered when taking steps to promote self-efficacy toward pregnancy planning among college students.