An automatic performance apparatus comprising: a storage section (2, 4) storing waveform data of a music performance based on a desired reference tempo; an acquisition section (1, S1) configured to acquire information designating a variable performance tempo; and an audio reproduction section (8, 1) configured to reproduce the waveform data stored in said storage section, said audio reproduction section performing, in order to reproduce the waveform data in accordance with the performance tempo, time axis expansion/contraction control on the waveform data to be reproduced in accordance with the relationship between the performance tempo and the reference tempo, said time axis expansion/contraction control being a control for increasing or reducing a reproduction time length of the waveform data without changing tone pitches of the waveform data, characterized in that said automatic performance apparatus further comprises: a determination section (1, S22, S25, S27, S28, S30, S31, S33) configured to determine whether a difference between the performance tempo and the reference tempo is greater than a predetermined threshold value, and thereby determine that reproduction of the waveform data should be limited when the difference is greater than the threshold value, and in that, the audio reproduction section (8, 1, S74, S75, S78, S80, S81, S84) is adapted to perform, when the determination section has determined that the reproduction of the waveform data should be limited, when a predetermined first condition that the performance tempo is too fast as compared to the reference tempo is satisfied, one of an operation for stopping the reproduction of the waveform data and an operation for continuing the reproduction of the waveform data with a time resolution of a reproduction process lowered, when a predetermined second condition that the performance tempo is too slow as compared to the reference tempo is satisfied, an operation for stopping the reproduction of the waveform data. a storage section (2, 4) storing waveform data of a music performance based on a desired reference tempo; an acquisition section (1, S1) configured to acquire information designating a variable performance tempo; and an audio reproduction section (8, 1) configured to reproduce the waveform data stored in said storage section, said audio reproduction section performing, in order to reproduce the waveform data in accordance with the performance tempo, time axis expansion/contraction control on the waveform data to be reproduced in accordance with the relationship between the performance tempo and the reference tempo, said time axis expansion/contraction control being a control for increasing or reducing a reproduction time length of the waveform data without changing tone pitches of the waveform data, a determination section (1, S22, S25, S27, S28, S30, S31, S33) configured to determine whether a difference between the performance tempo and the reference tempo is greater than a predetermined threshold value, and thereby determine that reproduction of the waveform data should be limited when the difference is greater than the threshold value, and in that, the audio reproduction section (8, 1, S74, S75, S78, S80, S81, S84) is adapted to perform, when the determination section has determined that the reproduction of the waveform data should be limited, when a predetermined first condition that the performance tempo is too fast as compared to the reference tempo is satisfied, one of an operation for stopping the reproduction of the waveform data and an operation for continuing the reproduction of the waveform data with a time resolution of a reproduction process lowered, when a predetermined second condition that the performance tempo is too slow as compared to the reference tempo is satisfied, an operation for stopping the reproduction of the waveform data.