Loss of data to be transmitted from a peripheral device to a host before a software hierarchy of the host side completely starts is prevented. In a time period before a host completely reached a normal operation mode from a sleep mode, data outputted from a receiver is stored in second buffer memory of a communication control device. When the host reaches the normal operation mode, an application hierarchy in the host transmits a transmission approval command to a control unit, and then the data is transferred from the second buffer memory to first buffer memory. Since communication between the host and the communication control device of the receiver is resumed and then the data stored in the first buffer memory is sent to the host through a USB line, loss of the data can be prevented.