The present invention relates to a singing audio editing assistant method and a singing audio editing assistant device which enable easy editing of an audio playback start portion of a lyric corresponding to a note in synthesis of a singing audio. The singing voice editing assistant method includes the steps: displaying singing waveforms represented by singing waveform data calculated based on score data representing a time series of notes and lyrics data representing words on a display device, on a note-by-note basis on a two-dimensional waveform screen having a pitch axis and a time axis, each singing waveform being displayed at a position located by a pitch and timing of a note corresponding to the singing waveform; and displaying a phoneme of each word at a pronunciation timing of thephoneme on the waveform screen. In the phoneme display step, information indicating a phoneme of a lyric is displayed at a sound production position of the phoneme in the waveform display screen.