In a disk drive using a motor frame, the motor frame is provided with a projection preliminarily formed to protrude on its principal surface. The projection has a slit formed at its base. A printed circuit board is inserted into the slit to be engaged with the projection. The motor frame is provided with a positioning boss fitted into a positioning hole formed in the printed circuit board. The motor frame is further provided with a plurality of board holding portions bent upward on the principal surface to be engaged with end portions of the printed circuit board. Preferably, the positioning boss is formed by coining.