The present invention relates to an AGC circuit, a AGC circuit gain control method, and a program for the AGC circuit gain control method, and may be applied to IC recorders, for example, as a portable recording/reproducing device, in order to ameliorate problems of listening to talk, music and the like during playback from IC recorders. In the invention, a signal level L1cyc is detected in units of the period of an input signal, and a recovery time constant r is switched on the basis of a decision as to the signal level L1cyc based on an average shift Lavg of the signal level L1cyc.