Abstract: A method is for automatically adjusting audio volume in a decoder that decodes digital audio data for each frame in which gain information that describes the audio volume of the frame is included. The method includes: storing a first gain information that is included in a preceding frame and used for decoding the preceding frame in a memory device; obtaining a second gain information that is included in a current frame; calculating a difference between the first gain information and the second gain information; adjusting the second gain information in accordance with the calculated difference; and decoding the current frame using the adjusted second gain information.