A withdrawable portable device mounting apparatus is provided in a vehicle audio system, in which a mount capable of mounting a portable electronic device is drawn out using an electromotive force with a very simple manipulation by pressing a drive button or the like. The apparatus may include a case, a front panel provided at a front surface of the case to have a control panel, a mounting unit loading hole, and a loading button, a drive unit configured to drive a mounting unit through a mounting unit loading hole of the front panel in a withdrawable manner, a loading unit mutually operated with the drive unit to allow the mounting unit to be drawn in or out, and a mounting unit inserted into the front panel in a folded state during a drawing-in operation, and unfolded through the mounting unit loading hole during a drawing-out operation.