PURPOSE: To decide lead/lag in a short time while reducing a circuit scale by deciding the lead/lag of inter-channel phase through the comparison of a frame number when two or more channels are used to send data.

CONSTITUTION: A phase decision reference output circuit 2 provides an output of a phase decision reference value A. A frame number output circuit 4 outputs a frame number M of a frame received via a 1st channel and a frame number N of a frame received via a 2nd channel. A 1st circuit 6 outputs an absolute value D of a reference value A-number N and a code signal of the absolute value D. A 2nd circuit 8 obtains a frame number M + absolute value D = correction value P when the sign of the absolute value D indicates a positive value and outputs a frame number M-absolute value D = correction value P when the sign of the absolute value D indicates a negative value. A decision circuit 10 decides that a frame of the 1st channel is advanced in the case of correction value P > reference value A and that a frame of the 2nd channel is advanced in the case of correction value P < reference value A.