To mass-produce semiconductor devices with high reliability in short time by suppressing the generation of vibration at the laser irradiation and moving a laser beam having homogeneous energy profile in one direction.A substrate is sucked onto a surface of a cylindrical rotator along the curvature of the rotator, the rotator is rotated, and a semiconductor film formed over the substrate is irradiated with a laser at one time. Moreover, a moving mechanism is provided in a rotational axis direction of the rotator, and an irradiation position is displaced at each rotation of the rotator. Alternatively, the irradiation position can be moved in the rotational axis direction while rotating the rotator.