A locking mechanism for installation on a device body, which includes an actuating element, includes a bezel having a through hole and a first positioning portion spaced apart from the through hole, and a locking element including a front operating portion extending through and movable along the through hole in a left-right direction, at least one guide pin extending in a front-rear direction, and an engaging portion. A press button is mounted slidably on the guide pin, and includes a contact portion adapted to be spaced apart from the actuating element in the left-right direction. The front operating portion is operable to move the press button between non-operative and operative positions, where the contact portion is adapted to be placed out of and in alignment with the actuating element, respectively. The engaging portion engages the first positioning portion when the press button is in the non-operative position.