The encoding apparatus includes an MDCT unit which transforms an inputted audio signal into a frequency parameter, for every predetermined time-frequency transformation frame length, and an MDCT coefficient encoding unit which encodes the frequency parameter. The encoding apparatus also includes a pitch cycle detection unit which detects a pitch cycle of the audio signal, a framing unit which frames the audio signal based on the detected pitch cycle, and a waveform modification unit which performs waveform modification on the audio signal framed based on the pitch cycle, in conformance with the time-frequency transformation frame length, and outputs the waveform-modified audio signal to the MDCT unit. A multiplex unit multiplexes the frequency parameter encoded by MDCT coefficient encoding unit and the pitch cycle, and outputs the multiplexed result as a bitstream.