A replaceable panel device has a panel (20), a locking subassembly (30) and a top cover (40). The panel is mounted on the top cover by the locking subassembly. The panel has a mounting hole (24) with a first arc groove (244). The locking subassembly is accommodated in the mounting hole of the panel and has a button (31) with a locking portion (314) and a spring (32). Two ends of the spring respectively contact with a particular portion of the mounting hole and the button. The top cover has a second arc groove (45) which corresponds with the first arc groove of the panel. The locking portion of the button passes through the first groove of the panel and the second groove of the top cover, and mates with the second arc groove by a return force of the spring to fix the panel and the top cover together.