This article examines the effects of electoral systems on issue ownership. This study argues that electoral rules significantly affect issue ownership because they prompt candidates to adopt different types of electoral campaigns. Compared to the single non-transferable vote (SNTV) system, the mixed-member majoritarian (MMM) system prods candidates to change the pattern of electoral campaigns from candidate-centred to issue-centred competition. In particular, partisan issue effects are more effective in gaining votes under the MMM. To support the argument, I find evidence from content analyses of party manifestos and multinomial logistic regression models of electoral surveys between the pre-reform and post-reform elections in Japan.