We investigate the Lee's model which is modified in such a way as the V state is in the unstable mass relation. A renormalization recipe is proposed, which reduces to the conventional one in the stable case but is essentially different from the latter in some respects. The result obtained by this method represents certainly the unstability of the V state. However, its decay character is more complicated than the ordinarily accepted exponential time-dependence. Some new features introduced by our method are discussed.