Abstract: In a mouse having two click switches with buttons, a motion detector and an additional control switch mechanism for a function of scrolling are provided. The additional control switch mechanism includes a first, a second, and a third switch for producing an up-scroll signal, a down-scroll signal, and a scroll mode selection signal, respectively when being actuated. A single actuator rod having a top push button is disposed to be able to incline opposite directions to selectively actuate the first and second switches and to be pushed down to actuate the third switch. The top push button is disposed between the click switch buttons. Alternatively, the third switch with a push button thereof is disposed at a sidewall of the mouse. In another arrangement, the third switch and the push button thereof are disposed between the two click switch mechanisms, and the first switch a push button thereof and the second switch with a push button thereof are disposed in a sidewall of the mouse.