Abstract: A musical tone generating apparatus for an electronic musical instrument utilizing a data compression system is disclosed. This musical tone generating apparatus is basically constructed by a memory storing difference data and a data reproduction circuit. The difference data is in advance obtained by converting a musical tone signal to be reproduced to digital sample data, effecting a linear prediction operation on the digital sample data to produce prediction data and calculating the difference between the digital sample data and the prediction data. The stored difference data are sequentially read from the memory. In the data reproduction circuit, the musical tone signal is reproduced by effecting a reverse operation of the linear prediction operation on the read difference data.