A musical tone generating apparatus has an waveform memory which stores original waveform data. One or two tone generating chips are be able to fixed on a print circuit board as elements of the musical tone generating apparatus. Each tone generating chip, provided on the print circuit board, sequentially generates waveform data of a plurality of musical tones at sampling periods having a predetermined length under time division control. Each tone generating chip sequentially carries out tone generating operations to generate the waveform data based on the original waveform data during time division channels which are obtained by dividing each one of the sampling periods when the musical tone generating section is used for tone generation. In the case where one tone generating chip is employed on the print circuit board, N samples of the original waveform data are read out from the waveform memory during each one of the time division channels to be used by the tone generating chip. In the case where two tone generating chips are employed on the print circuit board, the number of the original waveform data read out from the waveform memory for each tone generating chip during each time division channel is decreased from N to M which is less than N.