A mouse having a changeable pad is comprised of a case, at least one replacement board and a plurality of pads. The replacement board is installed in the bottom of the case. The pads are installed on both faces of the replacement board. When the pad on the first face of the replacement board becomes worn out, the replacement board can be turned over and the pad on the second face of the replacement board can be installed in the bottom of the case for increasing the pad's user life.