The purpose of this study was to refine the items on a scale measuring interprofessional collaborative competency that was developed by the authors in an earlier pilot study. A questionnaire-based study was conducted with a sample of 2133 health professionals using the reformulated questionnaire. Construct validity was tested by comparing the survey results with a covariance structure analysis and the domains of interprofessional collaboration competencies presented in previous studies. A second survey was conducted 2 weeks later with a sample of 571 nursing professionals, using the same survey form to test its reliability. We constructed a model comprising 29 observed variables and six latent variables (the Chiba Interprofessional Competency Scale: CICS29), and obtained the following values for the model's goodness of fit: GFI = 0.925, AGFI = 0.908, CFI = 0.950, RMSEA = 0.049. With regard to reliability, we obtained scores ranging from 0.65 to 0.77 for the intraclass correlation coefficients of the six domains. Compared with the interprofessional collaboration scales indicated in previous studies, the CICS29 was found to have subsumed the key concepts that should be configured as interprofessional collaboration competencies. The CICS29 appeared to have satisfactory levels of reliability and validity and is recommended as a scale for measuring competencies of interprofessional practice.