A driving motor comprises a rotor having a rotatably supported shaft, a rotor case rotating together with the shaft, a hub seat attached to the rotor case for mounting a disk hub and a chucking magnet for magnetically attracting the disk hub and a thrust ball bearing having a washer, a plurality s of balls and a retainer for holding the balls and supporting the load in the thrust direction of the rotor. The motor also includes a flatness control section which passes through the rotor case to contact the washer of the thrust ball bearing and controls the flatness of the washer and a position control section which passes through the rotor case to contact an inner circle surface of the washer of the thrust ball bearing and controls the washer in the thrust direction. The chucking magnet, flatness control section and position control section are integrally molded of resin.