A computer peripheral device for controlling scroll bars in different windows is provided. The computer peripheral device includes a plurality of scroll bar controlling units and a signal processing unit. These scroll bar controlling units are used for generating a scroll bar controlling signal. The signal processing unit is used for analyzing the scroll bar controlling signal. According to the scroll bar controlling signal, the scroll bars in different windows are correspondingly controlled. A method for controlling scroll bars in different windows is also provided. Firstly, the signal source of the scroll bar controlling signal is analyzed. According to the signal source, the scroll bars in different windows are correspondingly controlled. Consequently, the speed of switching different windows is increased, and the working efficiency is enhanced.