To prevent the occurrence of an underflow and an overflow of data without increasing the cost.

A clock deviation measurement part 71 measures the deviation of a clock from increase and decrease of the data quantity stored in a FIFO memory 15A. A control determination part 72 determines a position for executing a correction process and what kind of correction should be executed on the basis of the measurement result of the measurement part 71 and data stored in the FIFO memory 15A. A data quantity control part 73 executes the correction process by deleting or creating the data at the position for executing the correction process on the basis of the determination result of the determination part 72 and the data stored in the FIFO memory 15A and rewrites the data in the FIFO memory 15A with the corrected data.