A computer enclosure includes a chassis (10), a side panel (20), and a locking device (30). The side panel defines a securing hole (24). The locking device is attached to the chassis for locking the side panel to the chassis. The locking device includes a sliding member (50/60), a resilient member (80), and a driving member (40). The sliding member includes a cuneiform portion (52/62) and a protrusion (54/64). The protrusion is engaged in the securing hole of the side panel. The resilient member is used for urging the sliding member. The driving member has a pushing portion (48) corresponding to the cuneiform portion of the sliding member, for disengaging the protrusion of the sliding member from the securing hole of the side panel.