AbstractThe literature of electoral reform explains politicians' preferences and social forces such as working‐class power or expansions of the suffrage are the major factors that bring about a change in electoral rules. However, we argue that generational replacement and electoral issue effects lead politicians to introduce a new electoral system for their electoral survival in future. By examining Japan's surveys for pre‐ and postreform elections, we show that the entrance of new generation and salient issue concerns dissolve electoral bases of political parties and finally give rise to a change in the rules of the game for the greater electoral stability that political elites desire.