A mouse device includes a mouse shell, a switch module, and a key module. The mouse shell has an upper shell and a lower shell, and the upper shell and the lower shell are joined together to form a chamber. The switch module is disposed within the chamber and is suspended from an inner side of the upper shell. The key module is disposed on an outer side of the upper shell. The key module is vertically movable and has a trigger. The trigger enters the chamber through the upper shell to activate the switch module when the key module is clicked.