In this paper, the attitude dynamics of IKAROS, which is spinning solar sail, is presented. Multi Particle Model (MPM) and First Mode Model of out-of-plane deformation (FMM) are introduced to analyze the out-of-plane oscillation mode of spinning solar sail. Considering the thruster configuration of IKAROS, the force on main body and membrane by thruster plume as well as reaction force by thruster are integrated into MPM. The attitude motion after sail deployment or reorientation using thrusters can be analyzed by MPM numerical simulations precisely. The out-of-plane oscillation of IKAROS is governed by three modes derived from FMM. FMM is simple and valid for the design of attitude controller.