Adhesion strength between sputtered Ti thin films and Si substrate has been evaluated by using an internal stress in Ni thin films deposited onto the Ti thin films. The adhesion of the Ni film to the Ti film is very strong and the internal stress in the Ni film was found to be large enough to peel off the Ti film from the Si substrates. The tensile stress generated by the internal stress in the Ni film at the interface between the Ti film and the Si substrate was evaluated by finite element method. By this method, it became clear that when the value of the Ni film internal stress times the Ni film thickness was 150 N/m, the corresponding tensile stress at the interface was 10 MPa and this stress was enough to peel off the Ti film on an Ar ion bombarded Si substrate.