The present inventive concept discloses a button which comprising a body, a lighting control unit and a cap. The body comprises a side wall and a base, wherein the side wall of the body is substantially disposed around and protrudes from the base to form a first accommodating space between the base and the side wall of the body; the lighting control unit is disposed in the first accommodating space, and the lighting control unit comprises a UV light-emitting element and a switch, wherein the switch is used for switching on/off the UV light-emitting element; and the cap comprises a side wall and a top, wherein the side wall of the cap is substantially disposed around and protrudes from the top to form a second accommodating space between the top and the side wall of the cap, and the top has a portion corresponding to a position irradiated by light beams of the UV light-emitting element is substantially made of a UV penetrable material, and wherein the cap separably covers at least one of the body or the lighting control unit.