The annual fecal occult blood test is a very important method for colorectal cancer early detection through screening. Our aim was to assess psychometrics of instrument measuring beliefs related to fecal occult blood test uptake among Iranian middle-aged and elderly, based on the theory of planned behavior. This cross-sectional study was performed on 150 middle-aged and elderly who were randomly selected to participate voluntarily in Kermanshah, in the west of Iran. The studied constructs included attitude, subjective norms, perceived behavior control, and behavior intention. Data were analyzed with SPSS software (ver. 21.0). The mean age of the respondents was 59.1 years [SD: 6.73], in the range from 50 to 73. All of the loads of the exploratory factorial analysis were larger than 0.4. KMO was calculated as 0.756. Overall, four factors under investigation accounted for 82% of the variance in the hypothesized model. Cronbach’s alpha for the measured constructs of attitude, subjective norms, perceived behavior control, and behavior intention were 0.92, 0.88, 0.70 and 0.88, respectively. Our findings indicated the final scale to be adequately reliable and valid for measurement of these constructs for prediction of fecal occult blood test uptake among Iranian middle-aged and elderly.