Background: There is no agreement on the usefulness of the prostate-specific antigen (PSA) test for prostate cancer screening in young men in Japan. We believe that medical check-up departments in hospitals conduct prostate cancer screening in subjects under 40 years of age undergoing intensive health check-up for commercial reasons, and speculate that some medical doctors provide tacit consent for this action. To understand the prevalence of PSA testing in young men, the authors examined the age distribution of workers who underwent the PSA test. Methods: The authors used the 2009 intensive health check-up data of male workers aged 30–65 years ( n = 298) in a car-manufacturing company to investigate the status of prostate-cancer screening in young men. Multiple comparison was conducted by Tukey's method when the analysis of variance revealed significant difference. Results: According to the frequency distribution of age, 15.8% of the subjects were under 40 years of age. The mean PSA value increased with age, ranging from 1.0 ng/mL in subjects in their 30s’, to 2.0 ng/mL in subjects in their 60s’. The mean PSA level in subjects in their 60s’ was significantly higher than that in subjects in their 30s’ and 40s’. The percentage of subjects with serum PSA levels of 4 ng/mL or higher in subjects in their 30s’, 40s’, 50s’ and 60s’ were 2.1% (1/47), 1.6% (2/125), 4.4% (5/114) and 8.3% (1/12), respectively. Conclusions: One-sixth of male workers attending the health check-up program were under 40 years of age. According to the criteria of the Japanese Urological Association, this examination program included younger subjects who were not candidates for PSA screening.