Background: This study aimed to elucidate whether the demographics and personality traits of fathers, who are considered to be responsible for their families’ well-being, influence the fathers’ subjective well-being.

Purpose: To investigate the relationship between the personality traits and well-being of fathers of preterm and term infants; and related factors.

Design: Descriptive sampling was used in a cross-sectional study.

Methods: The “Personality Inventory Scale” and “Subjective Well-Being Scale” were administered, which had respective internal consistencies of 0.83 and 0.95.

Results: (1) The two groups reported moderate subjective well-being; (2) there was no significant difference in the overall personality traits between the two groups; (3) In both groups, the fathers’ subjective well-being increased with age; (4) In both groups, the core subjective well-being of fathers was higher than that of the noncore family, and their subjective well-being was not significantly affected by the number of children or by family socioeconomic status. In short, in both groups, the fathers’ subjective well-being was influenced by their personality, age, and family structure.

Practice implications: Examining issues related to the personality traits of fathers of preterm infants is useful not only in the formulation of care and medical systems, solutions, and strategies for preterm infants but also in understanding family relationships to enhance subjective well-being. The present findings serve as a reference for the development of family-centered, whole-person health care.