PURPOSE: To easily execute operation for finely adjusting a tone even in playing by forming tone fine adjustment operation data by indicating a relative fine adjustment direction by a 1st and a 2nd operator.

CONSTITUTION: A 1st operator indicates the increment of fine adjustment quantity related to a prescribed tone determination element and the 2nd operator instructs the reduction of fine adjustment related to the prescribed tone determination element. An operation data forming means forms operation data related to the prescribed tone determination element in accordance with the operation of the 1st and 2nd operators. A control means controls the change of a tone parameter related to the prescribed tone determination element out of a plurality of tone parameters generated from a tone parameter generating means in accordance with the operation data formed by the operation data forming means. Consequently, operation for tone fine adjustment can be extremely easily executed and operation for finely adjusting a tone can be extremely easily executed even in playing.