A rack includes an enclosure, a tray and a locking member. The enclosure defines a receiving space. The enclosure includes a side wall. The side wall includes a rail. A locking slot is defined in the side wall. The tray is received in the receiving space and is slidable on the rail. The tray includes a side plate. An operating hole is defined in the side plate. The locking member includes a first end, a second end opposite to the first end, and a locking portion located on the second end. The first end is attached to an inner surface of the side plate. The locking portion is engaged with the locking slot.