A read address from a memory and a write address to the memory are transmitted from a VT pointer circuit on an active side to a VT pointer circuit on a standby side in order to eliminate a difference between pointer values of the VT pointer circuits on the active and the standby sides, which is caused by a difference between the phases of the read address from the memory and the write address to the memory of the VT pointer circuits on the active and the standby sides, and the read and the write addresses on the standby side are overwritten with the transmitted address values. As a result, the address values can be made to match both on the active and the standby sides, and also the pointer values can be made to match.