To exactly guide a performance to express empathy by not only simple guide of key touch but also delicate strength of finger tip feeling.

A CPU 6 reads music data containing sound pitch data, initial velocity data, and after velocity data from a ROM 7, to guide a performance. In this case, before starting key operations to push keys on a keyboard 1 according to the sound pitch data, LEDs in a LED group corresponding to the keys are made to be turned on in a light quantity based on the initial velocity data, and after starting the key operation, LEDs of a LED group corresponding to the keys are made to be turned on in a light quantity based on the after velocity data.