To enable even a musical piece data changing in reproducible timing in the middle of the musical piece to be reproduced in synchronization from the same timing.

An MPS 3 part is begun to be reproduced from a reproduction start position P' traced back to earlier than an instructed reproduction start position P. Mute reproduction is, however, performed in the period from the reproduction start position P' to the timing corresponding to the reproduction start position P. When the progression of the MPS 3 part attains the timing corresponding to the reproduction start position P, the mute is canceled and the reproduction of an MIDI part is started simultaneously therewith.