When reading/writing data between a computer and a mass storage of a mass storage apparatus, the data transmitted from the computer are immediately confirmed by using an output device attached to the mass storage apparatus. There is provided a control device 101 for interpreting a command received from a control device 120 and for carrying out an output processing to an output device 103 if it is decided that the received command is a command for giving an instruction for outputting data stored in a mass storage 102 to the output device 103 in a state of a connection to the control device.