Background and Objective: Detecting and diagnosing it early can greatly reduce the mortality rate. The aim of the present study was to determine the efficacy of the prostate cancer screening promotion program based on the health action process approach (HAPA) in men aged 50 to 69 years in Kermanshah using a Smartphone application. Materials and Methods: The present study was a quasi-experimental study that was conducted in two intervention and control groups (40 people each) in 2023. Information was collected using a questionnaire. The obtained information was analyzed in SPSS software version 16. Results: After the program was implemented, a significant difference was seen in the average scores of action self-efficacy (P < 0.001), intention (P < 0.001), action planning (P = 0.005), coping planning (P = 0.042), coping self-efficacy (P = 0.012), recovery self-efficacy (P < 0.001) and self-monitoring (P = 0.016) between the intervention and control groups. The effect size for risk perception, outcome expectancies, action self-efficacy, intention, action planning, coping planning, coping self-efficacy, recovery self-efficacy and self-monitoring are 0.44, 0.43, 0.97, 0.77, 1.12, 0.46, 0.58, 0.92 and 0.55 were estimated, respectively. Conclusion: The use of Smartphone applications program based on the HAPA can provide valuable insights in enhancing the acceptance of prostate cancer screening tests. It is recommended to utilize these applications for the development and implementation of men's health promotion programs.