PURPOSE: To provide a phase difference coding circuit by which a the number circulation is counted at one location.

CONSTITUTION: A NAND g00 and inverters g01-g62 are connected in series and an output of the inverter g62 and a pulse PA are given to the NAND g00. Furthermore, the NAND and each inverter have an output to a succeeding stage and an output to a pulse selector 20 via one inverter (g00-g620). Moreover, each of the inverters g000-g620 is provided with each of inverters g001-g621 in addition and an inverter g311 is connected to a pulse generator 40. The pulse generator 40 is made to be the inverter constitution similar to that of a ring delay pulse generating circuit 10 and a clock of a counter 1 is a signal rising at a point A and a clock of a counter 2 is a signal inverted by the inverter 41 and rising at a point B. Two counters are operated at one location by using the clock.