PURPOSE: To attain the correct indications for a horizontal line, a vertical line and a 45° line respectively by starting a counter only when the coincidence is obtained between the output pulses of an X-axis detecting circuit or a Y-axis detecting circuit only or the output pulses between both detecting circuits.

CONSTITUTION: The output given from a shift detecting mechanism 1 of a mouse device is applied to an X-axis detecting circuit 2 and a Y-axis detecting circuit 3 and used as the output pulses of an X-axis UP4/DOWN5 and Y-axis UP6/DOWN7 respectively. These pulses are applied to a gate circuit 16 controlled by a control circuit 13 which works after receiving a command given from a host system through a reception circuit 12. Thus, only the X-axis UP/ DOWN pulses 4 and 5 are applied to an X-axis counter 8 and then sent to the host system via a selector 10 and a transmission circuit 11 with a horizontal line operation command for example.