A music sound generator imitates released key string vibration sounds (RKSV) and cabinet resonances of an acoustic piano. When a key is pressed, waveform is readout from a normal music sound waveform memory 15. The normal sound waveform is inputted into a filter 21, and inputted into a filter 22 through a band-pass filter 33. Output waveform of a cabinet resonance waveform memory 17 is inputted into a filter 23 when the key is pressed. Outputs of the filters are synthesized by an adder 27 through multipliers 24 through 26. When the key is pressed, a cut-off frequency of the filter 22 is sufficiently low and RKSV is not generated. If the damper is not on when key-releasing, the cut-off frequency is returned to normal and RKSV is generated. A level controller 32 attenuates the RKSV and the cabinet resonance for a longer time than the normal music sound.