In a wireless receiver that receives an electric signal that has undergone digital modulation, a sample-hold circuit converts a wireless modulated signal, which is a continuous time signal, to a discrete time signal, and the frequency band is converted and selected by means of a band-pass filter. A demodulation circuit carries out demodulation based on the instantaneous value of the voltage amplitude of the modulated signal. A shut-down circuit further effects adaptive control of the circuit shut-down time to minimize the circuit activation time while ensuring that the demodulation error rate of the demodulated baseband signal satisfies a value stipulated by the communication standard.