PURPOSE: To prevent a musical sound from being broken owing to truncation by selecting a channel among allocated automatic performance data on the basis of key-OFF time information corresponding to each automatic performance data unless there is a free channel among time-division channels.

CONSTITUTION: This electronic musical instrument has the time-division channels for an automatic musical performance, the automatic performance data are assigned to the time-division channels and supplied to a sound source circuit, and musical sound signals are generated on the basis of the automatic performance data assigned by the channels. A buffer a2 is a key-OFF preparation channel buffer and stored with the channel number of a channel to be keyed OFF at next timing on the basis of the remaining gate time of a remaining gate time buffer a3. Then when there is no free channel to be truncated in a key-OFF channel buffer a1, a channel to be truncated is selected in the key- OFF preparation channel buffer a2.