A feeding device of a slot-in disk drive is disposed in a casing of the disk drive and includes a traverse. A bolt is disposed on and protrudes from a side of the traverse. A flange extends from the side of the traverse near the bolt. A pre-stressed piece is a bended elastic body. One end of the pre-stressed piece is fixed to the flange of the traverse, and the other end is fixed to the casing. The pre-stressed piece presses the traverse downward by its elastic force. A slider includes a protrusion with a groove formed on a side of the protrusion. The bolt is inserted into and slides within the groove. The groove includes an unloading end, an inserting portion and a loading end. An opening is formed on the upper surface of the slider near the inserting portion for reducing the thickness of the disk drive.