To solve the problem that a conventional digital calibration type analog/digital converter is disabled from settling calibration within a preamble term of a packet signal.

While utilizing a beacon signal, a polling signal or a signal of another user or while utilizing a signal applied from a transmission unit to a reception unit, digital calibration of an analog/digital converter is performed. For power consumption reduction, in particular, the circuit is partially or entirely brought into sleep mode, excepting for data reception and analog/digital converter calibration, a signal monitoring unit detects existence of another signal, and the circuit in a sleep state is caused to wake up from the sleep mode to perform the calibration of the analog/digital converter.