Although the morbidity rate of prostate cancer has increased with 2.3 times in these 10 years in Japan, little is known about the changes in the prevalence of latent prostate cancer. To understand changes in the prevalence of latent prostate cancer, a retrospective analysis was performed. Forensic autopsy findings from Tochigi Prefecture between September 2012 and February 2014 were collected. Two cross sections, from the base and apex of the prostate, were examined histopathologically. The prevalence of latent prostate cancer was compared with findings from forensic autopsies performed between August 2002 and July 2005 in the same region. The prevalence of latent prostate cancer in both groups was similar, showing an overall prevalence of 13.6% and 12.2% and a Gleason score >6 of 6.2% and 7.1%, respectively. When prevalence was compared by cause of death, the values were similar for both groups. The prevalence of latent prostate cancer in this Japanese population did not show any significant change over the past 10 years. The dramatic increase in morbidity rate for prostate cancer could be from the increase in prostate-specific antigen screening and subsequent referral to urologists.