The objective of this retrospective observational study was to investigate the impact of fecal occult blood test (FOBT) as colorectal cancer (CRC) screening by primary tumor location. We compared the risk of requiring treatment for advanced disease and total medical costs per patient between CRC patients who underwent FOBT within 1 year before initial treatment for CRC and those who did not, using the JMDC Claims database, large-scale health insurance claims and checkup data in Japan. Treatment for advanced disease was defined as (1) nonendoscopic therapy or (2) chemotherapy or radiotherapy, performed during the follow-up period. A total of 1194 participants with CRC (right-sided, 22.2%; left-sided, 60.4%) who initiated treatment between 2010 and 2016 and underwent health checkups within 1 year before the initial treatment were enrolled and followed up for an average of 46.1 months. A significantly lowered risk ratio (RR) of chemotherapy or radiotherapy and total medical costs were observed in FOBT group for left-sided CRC [RR = 0.78 (95% confidence interval, 0.63–0.97), mean and median costs = 4.1 vs. 5.6 and 2.4 vs. 2.9 million JPY; P = 0.018], while they were not observed for right-sided CRC [RR = 0.88 (95% confidence interval, 0.61–1.28), mean and median costs = 4.0 vs. 4.1 and 2.7 vs. 2.9 million JPY; P = 0.995]. This study demonstrated the improved outcomes by FOBT for left-sided CRC, whereas its impact was limited for right-sided CRC.