To suppress the generation of error and improve the precision by providing an auxiliary memory part in a transmitting part, transmitting the value of a toggle counter as first distance data with a prescribed period, and also transmitting the value of the auxiliary memory as second distance data at a prescribed timing.

A transmitting part 2 counts the pulse number with a toggle counter 2b and an auxiliary memory part 2e for the period from input time T1 of a switch to the interruption time T2 thereof (input period T), transmits the value of the toggle counter 2b as distance data X at a prescribed period, and transmits the count value of the auxiliary memory part 2e as distance data Y at a prescribed timing. The arithmetic part 4c of a receiving part 4 adds the traveling distance of the memory part 4d every time when the traveling distance A by the distance data X reaches a unit traveling distance, and outputs the result as the latest total integrated traveling distance. The traveling distance B based on the distance data Y is compared with the total traveling distance C of the traveling distance A received in the input period T, and the latest integrated traveling distance is corrected by the difference and outputted to the circuit 4e.