Phase structure of CP(N-1) model with topological term

CP(N-1) model with topological term is numerically studied. The topological charge distribution P(Q) is calculated and then transformed to the partition function Z($theta$) as a function of $theta$ parameter. In the strong coupling region, P(Q) shows a gaussian behavior, which indicates a first order phase transition at $theta =pi$. In the weak coupling region, P(Q) deviates from gaussian. A bending behavior of resulting F($theta$) at $theta eq pi$, which might be a signal of a first order phase transition, could be misled by large errors coming from the fourier transform of P(Q). Results are shown mainly for CP(3) case.