PURPOSE: To simply switch sensitivity to two steps or more by providing the mouse with an output part for outputting a moving distance detecting output as the pulse strings of plural measuring units and a sensitivity control switch for selecting and specifying the output of the pulse string of one measuring unit out of the outputs of the output part.

CONSTITUTION: The rotation of a ball 4 is transmitted to rotary encoders 6, 8 through the rotation of rollers 5, 7 and decomposed to X and Y axis directions, which are detected. The outputs of the encoders 6, 8 are connected to the inputs of two pairs of frequency dividing circuits 9A, 10A and 9B, 10B and one end of the sensitivity control switch 2. When the switch 2 is set up to low sensitivity, three-divided frequency results of output pulses from the encoders 6, 8 are sent to a host computer. In the case of medium sensitivity and high sensitivity, two-divided frequency results and output pulses themselves are respectively sent.