PURPOSE: To enable demonstration performance from which monotonousness is removed by varying a feeling of music by varying its timbre and rhythm at specific timing.

CONSTITUTION: A keyboard 1, a panel operation part 2, a CPU 3, a ROM 4, a RAM 5, a timer 6, and a sound source circuit 7 are connected mutually through a system bus 11. Data for demonstration performance which are stored in the ROM 4 includes a quantization number and envelope data for varying the feeling of the music and other parameters PARA1 - PARAm in addition to note data. A sound is generated while information for varying the music feeling in the ROM 4 is referred to. Consequently, the demonstration performance which is not monotonous and rich in variation becomes possible.