To avoid falling into a divergent state by such control that the update of weighting is turned off when detecting no signal or the like in a reproducing device provided with an adaptive equalizer.

The adaptive equalizer is provided with; a plurality of unit delay means for successively delaying input signals a plurality of main line system weighting means for weighting delay signals respectively; a main line system integration means for updating and changing the weighting; a main line system summing means for summing output signals; a plurality of weighting means for examination which weight outputs of the plurality of unit delay means; an integration means for examination which updates and changes the weighting more times by the number of times of integration, which is smaller than that of the main line system integration means; a summing means for examination for summing output signals of the plurality of weighting means for examination; and an update determination control means which performs control to turn on the output side of the main line system integration means in the case that the output signal of the summing means for examination is within a prescribed threshold range, and to turn off the output side of the main line system integration means in the case that the output signal is outside the prescribed threshold range.