Abstract: A forced compression type pump including a cylindrically shaped pump case, an eccentric rotating body shaft-supported on said pump case at an eccentric position relative to said pump case and a compressing and forcibly sending member movable in a radial direction or said eccentric rotating body and adapted to be brought into press contact with the interior wall of said pump case, characterized in that the interior space is formed at the central part of said eccentric rotating body, a plurality of guide grooves are formed in a radial direction from said interior space to the circumferential surface of said eccentric rotating body, a plurality of circumferentially contacting cylindrical body inserted in said guide grooves and movable freely in a radial direction are formed, said plurality of circumferential contacting cylindrical body are in a planetary relationship relative to said central cylindrical body and the outer circumferential surfaces of said circumferentially contacting bodies are brought into press