An electronic device includes a housing defining an opening, a button mechanism, and a fixing portion. The button mechanism includes a button cap depressibly received in the opening, a light guiding plate with the button cap mounted on a first side thereof, and a connecting portion. The connecting portion is mounted on an opposite second side of the light guiding plate, and includes a resisting member, and a tab protruding from the resisting member. The fixing portion is received in the housing, and includes a block defining a slot with the tab extending therethrough, an light source for illuminating the light guide plate, a switch to switch on or off the light source and the electronic device. The switch is configured to switch on or off the light source and the electronic device. The button mechanism is depressible so as to enable the resisting member to actuate the switch.