A general formula for the radiation pressure acting on a thin rigid circular disk is derived from the theory of the previous paper. Motion of the disk under action of the wave and diffraction of the wave due to the disk are taken into account. Constants which may be calculated by the use of the oblate spheroidal functions necessary in obtaining the radiation pressure are given in the table. Numerical calculation for disks of various weight with the ratio of the circumference of the disk to the wavelength of sound up to 3.5 is carried out.