A slot-in disk drive device has a drive unit for providing power to move a slider and thus a sliding plate attached to the slider. Guiding slots on the sliding plate rotate a transmission bar. A guide pin is disposed on the transmission bar and moves with a loading stick. One end of a receiving bar is formed with a locking slot. A substrate having inclined slots arranged in parallel and used for guiding the receiving bar. A locking member mounted on the disk drive device has a stopper edge located on moving path of projecting guide pin of the transmission bar and a locking pin. One end of a pulling spring is fixed to the locking member so that the locking pin locks with the locking slot. One end of a restoring bar is mounted on the substrate, and a restoring torsion spring supports and restores the receiving bar.