Objective: This study aimed to explore pharmacists' counseling for dementia by developing a measurement tool based on the Theory of Planned Behavior. Methods: A survey was applied online to community pharmacists; in total, 190 community pharmacists participated in the study. Exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and Mann-Whitney U test were performed. Results: A six-factor structure was obtained from the EFA, and the CFA confirmed the structure. These factors explained 71.294% of the total variance. The Cronbach's alpha coefficients for the factors ranged from 0.728 to 0.913. In addition, the pharmacists rated themselves as having positive attitudes and intentions toward counseling for dementia. Differences in these factors were found between the groups based on their participation in vocational training on dementia. Conclusion: The developed measurement tool had a satisfactory construct and convergent and discriminant validities and reliabilities. Practice implications: The developed measurement tool can be used to investigate pharmacists’ self-reported counseling for dementia and can also be applied to the counseling behavior of pharmacists in various health conditions.