Electronic piano includes speakers arranged on its front side region and another speaker provided at a back position of the piano. Waveform memory provided in a tone generator section has prestored therein sets of four-channel waveform data, each of the sets corresponding to a tone. The four-channel waveform data are data recorded from a natural musical instrument via four microphones installed at sampling positions corresponding to the above-mentioned speakers. The microphones are installed with the on-microphone setting in which the microphones are positioned close to sounding members of the natural musical instrument. In response to depression of a key, any one of the sets of four-channel waveform data, corresponding to a tone pitch designated by the key depression, is read out from the waveform memory, so that the four-channel waveform data are supplied in parallel to the individual speakers.