To reduce a designer's labor in a design stage by restraining time required for altering each of data.

A storage section 301 stores basic data which are normal performance data, or branch data which are data for branching a performance from the performance based on the basic data. An interrupting section 303 interrupts the reproduction of the basic data when reaching predetermined branch timing. A switching section 304 switches data to be reproduced to one of a plurality of branch data when the reproduction of the basic data is interrupted by the interrupting section 303. A resuming section 305 resumes the reproduction of the basic data at the end of the performance based on the one branch data switched by the switching section 304.