11 transmits a packet including the clear feature command to the device 12 step 22 the device 12 receives this clear feature conventionally the device 12 operates would not transmit the stall packet however in the present invention the cf detecting portion 19 a detects the clear feature command therefore the device 12 transmits the stall packet for verification to the host pc 11 step 23 since the stall packet is transmitted the protocol phase is matched between the host pc 11 and the device 12 even if the stall packet is erroneously recognized or not thereafter the host pc 11 again transmits the clear feature packet step 24 in this case the device 12 determines that the clear feature command is received for the stall packet transmitted in the step 23 and transmits the status information csw in response to the clear feature command this status information is transmitted as the bulk in data packet via the second end point 17 accordingly the status information is transmitted and received between the host pc 11 and the device 12 the data transfer is started again when the transaction is executed for the status information moreover when the device 12 erroneously recognizes the signal received from the host pc 11 as the clear feature command deviation between protocols on both devices can be prevented when the device 12 transmits the stall packet to the host pc 11 1 when the host pc 11 erroneously recognizes the stall packet such erroneous recognition is detected by the cf detecting portion 19 a in particular when the host pc 11 erroneously recognizes that.