To accurately and easily inspect transmission when data and a clock signal designating timing of the data input are transmitted in parallel.

When inspection of transmission, in which the data and the clock signal designating input timing of the data are transmitted in parallel, is carried out in inspection of the storage system having a plurality of disk drive devices, the data having pulse waveform temporarily changed to a predetermined condition by the predetermined data output timing and the clock signal are outputted on the transmission side of the transmission. On the receipt side of the transmission, the data and the clock signal are fetched in, and by the predetermined data input timing generated synchronously with the fetched-in clock signal, the inputted data are latched. Based on the latched data, it is inspected whether the data are transmitted normally or not.