A mouse includes a left button, a right button, a touch sensing unit and a processing unit. The left button and the right button generate click signals in response to click operations. The touch sensing device generates touch positional signals when the left or right button is touched. The processing unit is used to receive the touch positional signals, calculate y-coordinate values of all points in the touched areas; select two significant points respectively from the left touched area and the right touched area; compare the y-coordinate values of the two significant points to generate a comparison result; confirm a current operated mode; if the confirmed operated mode is a left handed operation, send a control signal with a left-button identifier to a computer configured therewith; if the confirmed operated mode is a right handed operation, send a control signal with a right-button identifier to the computer configured therewith.