This paper studies stability of coalition structures in the apex game by the use of Bloch’s (1996) model of dynamic coalition formation. In our model, players’ payoffs are given by the coalition values and a cost for proposal is newly introduced. We study stable coalition structures by the subgame perfect equilibrium and we show that in the apex game stable coalition structures depend on the cost for making a proposal and who the first proposer is. As opposed to the static analysis by Hart and Kurz (1983), it turns out that the apex may form a two-person coalition with a minor player.