The relationship between geographical accessibility to gambling venues and the prevalence of pathological gambling is still unknown. This study aimed to reveal this relationship in Japan as well as its variation by subpopulation. A cross-sectional study was conducted, based on an original web-based survey to understand the level of pathological gambling depending on accessibility to pachinko parlours. Pathological gamblers were measured using the Japanese version of the South Oaks Gambling Screen. Accessibility to gambling venues was defined as the number of pachinko parlours within a 1.5 km radius from home. Moreover, the study adopted the instrumental variable approach to solve the potential endogeneity problem. The results showed that the accessibility was not significantly associated with pathological gambling in general, but that the effects of accessibility varied by subpopulation. Accessibility was significantly and positively correlated with pathological gambling for men and people in low-income areas, but this was not so for women and people in high-income areas. The study’s findings show the importance of the neighbourhood environment and could help in implementing more effective interventions for pathological gamblers.