Abstract: In a data transmit/receive method for plurality of devices connected by a 1394 bus, a receiving device obtains a device-specific number of a transmitting device when starting to receive data. When a bus reset occurs, the receiving device again obtains the device-specific number from the transmitting device, and checks whether the device-specific numbers before and after the bus reset match. If the device-specific numbers differ, the receiving device obtains the device-specific number from all devices connected to the bus. If a device with the same device-specific numbers as prior to the bus reset is present among the obtained device-specific numbers, the channel number of the bus used for the transmitting of data is determined, and the receiving device starts receiving with that channel number. Then device authentication with the transmitting device is carried out, and key information for solving the encryption is obtained.