A mounting apparatus configured to mount a power supply unit to an electronic device includes a case and a locking member. The case includes a side wall and a division plate. A receiving space is defined between the side wall and the division plate. The receiving space receives the power supply unit. The division plate defines a locking hole. The locking member is pivotally mounted on the side wall. The locking member includes a pressing pole and a locking tab. The locking member is rotated on the side wall to have the pressing pole press a power supply unit and the locking tab positioned in the locking hole.