Objective To clarify the effects of mental health and physical function in association with colonoscopy-related pain. Methods The mental health and physical function were evaluated using the Japanese version of the SF-8 Health Survey questionnaire. Poor physical status was defined as a physical component summary (PCS) < 40 and poor mental status as a mental component summary (MCS)= 70 mm and insignificant pain as VAS < 70 mm. The background and colonoscopic findings were compared in patients with significant and insignificant pain. Patients This study evaluated consecutive Japanese patients who were positive on fecal occult blood tests and underwent total colonoscopy. Results Of the 100 patients, 23 had significant and 77 had insignificant colonoscopy-related pain. A multiple logistic regression analysis showed that MCS < 40 [odds ratio (OR) 6.03; 95% confidence interval (CI) 1.41-25.9, p= 0.0156], PCS= 300 seconds to reach the cecum (OR 4.13; 95% CI 1.16-14.7, p= 0.0281) were independent risk factors for colonoscopy-related pain. Conclusion The mental health and physical function are important determinants of colonoscopy-related pain. Evaluating the mental health and physical function of patients prior to colonoscopy may effectively predict the degree of colonoscopy-related pain.