We measured carbon and nitrogen stable-isotope ratios in the livers of 130 brown bears (Ursus arctos) killed by hunters in two coastal areas of Hokkaido, Japan, from 2003 to 2004 to analyze the diets of individual bears, particularly maize. In both study areas, bears suspected of damaging maize, whose diets were higher in the C4 plant component, were mainly observed during late summer and autumn. Wide variation in the C4 plant component indicated that individual bears have differing degrees of dependence on maize, suggesting differential foraging behavior among the individual bears. We found that a stable-isotope ratio analysis of individual Hokkaido brown bears can serve as a tool to review the effectiveness of control killing and to monitor trends in maize consumption by local populations of bears.