In a radio-controlled device for measuring time, a demodulating unit demodulates the time information from the received electric signal based on amplitude information of the target radio wave. The amplitude information is obtained from in-phase and quadrature-phase components of the target radio wave. A phase calculator calculates phase data associated with a phase of the target radio wave based on the in-phase and quadrature-phase components. A variability calculator calculates a variability of the phase data of the target radio wave relative to a reference phase. The reference phase changes at a constant rate in time according to a frequency error. The frequency error is contained in the reference signal relative to a frequency of the target carrier wave. A reception determining unit determines whether reception of the radio-controlled device is good based on the calculated variability.