An electronic musical instrument comprising: means for determining, in accordance with a user operation on at least one operation element, first waveform data (a) from a plurality of pieces of waveform data, amplitudes of the first waveform data (a) changing over time; means for detecting an amplitude envelope of a waveform indicated by the first waveform data (a); characterized in that the electronic musical instrument further comprising: means for generating normalized data (b) in which amplitudes of the waveform are normalized to be kept at a constant amplitude, by multiplying an amplitude envelope calculated by a envelope calculator by the waveform of the first waveform data (a); means for amplifying at least a part of the waveform in the normalized data (b) to generate amplified data (c); means for clipping at least one region of a positive region and a negative region of the waveform included in the amplified data (c) at a certain clipping level to generate clipped waveform data (d); means for changing amplitudes of the waveform indicated by the clipped waveform data (d) to amplitudes of the waveform before performing normalization; and an inverse correction amplifier for adjusting a distortion amplifier envelope generated by a distortion amplifier EG so as to cancel an influence of the normalization based on the detected amplitude envelope, wherein the detected amplitude envelope of the waveform indicated by the first waveform data (a) is multiplied by the distortion amplifier envelope in the inverse correction amplifier to obtain an adjusted envelop as a result thereof, said adjusted envelop is multiplied with the clipped waveform data (d) by the means for changing amplitudes of the waveform indicated by the clipped waveform data to generate a distortion waveform data (e). means for determining, in accordance with a user operation on at least one operation element, first waveform data (a) from a plurality of pieces of waveform data, amplitudes of the first waveform data (a) changing over time; means for detecting an amplitude envelope of a waveform indicated by the first waveform data (a); characterized in that the electronic musical instrument further comprising: means for generating normalized data (b) in which amplitudes of the waveform are normalized to be kept at a constant amplitude, by multiplying an amplitude envelope calculated by a envelope calculator by the waveform of the first waveform data (a); means for amplifying at least a part of the waveform in the normalized data (b) to generate amplified data (c); means for clipping at least one region of a positive region and a negative region of the waveform included in the amplified data (c) at a certain clipping level to generate clipped waveform data (d); means for changing amplitudes of the waveform indicated by the clipped waveform data (d) to amplitudes of the waveform before performing normalization; and an inverse correction amplifier for adjusting a distortion amplifier envelope generated by a distortion amplifier EG so as to cancel an influence of the normalization based on the detected amplitude envelope, wherein the detected amplitude envelope of the waveform indicated by the first waveform data (a) is multiplied by the distortion amplifier envelope in the inverse correction amplifier to obtain an adjusted envelop as a result thereof, said adjusted envelop is multiplied with the clipped waveform data (d) by the means for changing amplitudes of the waveform indicated by the clipped waveform data to generate a distortion waveform data (e). means for generating normalized data (b) in which amplitudes of the waveform are normalized to be kept at a constant amplitude, by multiplying an amplitude envelope calculated by a envelope calculator by the waveform of the first waveform data (a); means for amplifying at least a part of the waveform in the normalized data (b) to generate amplified data (c); means for clipping at least one region of a positive region and a negative region of the waveform included in the amplified data (c) at a certain clipping level to generate clipped waveform data (d); means for changing amplitudes of the waveform indicated by the clipped waveform data (d) to amplitudes of the waveform before performing normalization; and an inverse correction amplifier for adjusting a distortion amplifier envelope generated by a distortion amplifier EG so as to cancel an influence of the normalization based on the detected amplitude envelope, wherein the detected amplitude envelope of the waveform indicated by the first waveform data (a) is multiplied by the distortion amplifier envelope in the inverse correction amplifier to obtain an adjusted envelop as a result thereof, said adjusted envelop is multiplied with the clipped waveform data (d) by the means for changing amplitudes of the waveform indicated by the clipped waveform data to generate a distortion waveform data (e).