The Physical Health Attitude Scale (PHASe) is an internationally valid and reliable scale for assessing mental health nurses' attitudes toward providing physical health care to people with serious mental illness. This study translated the PHASe into traditional Chinese and evaluated its psychometric properties in the context of Taiwan. A descriptive, cross-sectional study design was adopted, and convenience sampling was used to recruit 520 mental health nurses from 11 hospitals across Taiwan. Data were collected between August and December 2019. Brislin's translation model was used for the validation process. Exploratory factor analysis and confirmatory factor analysis were used to establish the construct validity of the scale, and Cronbach's alpha and composite reliability were used to determine its reliability. The factor analysis results revealed that the 4-factor 17-item traditional Chinese version of the PHASe accounted for 44.2% of the total variance. Each factor had adequate internal consistency (Cronbach's alpha = 0.70 to 0.80). We also noted significant differences between groups with different attitudes, demonstrating known-group validity. Our findings indicate that the traditional Chinese version of the PHASe is acceptable for evaluating nurses' attitudes toward providing physical health care in Taiwan.