The passive electric potential CT (computed tomography) method was applied to the identification of Z-shaped delamination existing in composite material. The electric potential distribution on piezoelectric film pasted on composite material is influenced by delamination parameters. The identification of delamination parameters from electric potential distrubution is an inverse problem. We proposed inverse analysis scheme for identifying delaminations and showed its applicability. The electric potential distribution for mountain-shaped array of delaminations was examined.