To test the reproduction of a sequence easily in a short time by using trace information without disconnecting a cable from a host device and a peripheral device.

If the sequence becomes abnormal during a communication with the host device 30, a host I/F board 20 breaks the communication with the host device 30. A channel control part 55 and a channel emulation control part 57 reproduces the sequence according to the trace information stored in the trace control part 56. The channel control part 55 analyzes the cause of the abnormality while reproducing the sequence.