An exemplary electronic device includes a casing with a slot defined in an outer face of the casing, a through holed defined in the slot, and a switch module. The switch module includes a switch received in the casing, and a slidable button embedded in the slot. The slidable button includes an operating portion received in the slot and abutting an outer face of the casing, a holding portion extending outwardly from the operating portion and through the through hole, and two elastic arms respectively extending outwardly from two lateral sides of the holding portion. Each elastic arm includes a connecting section extending outwardly from the holding portion and a locking section protruding outwardly from the connecting section towards the operating portion. The locking sections of the elastic arms abut an inner face of the casing, whereby the slidable button is fixed to the casing.