To provide a system capable of storing only a necessary parameter group as a setting data.

In a storage means of a setting data processing system, a plurality of sets of setting data composed of a plurality of kinds of parameter groups regarding musical sound control are stored, and a registration memory data group composed of a plurality of registration memory data is included in classifications of the parameter group. According to "move" operation on a screen, a structure of the parameter group in a setting data of a desired set (REG_002) is displayed by a "data to read" button. By "read" operation, the setting data of the set is read out from the storage means and held in a random access memory (RAM) so as to be set, and the parameter group of the setting data is reflected to musical sound control. By a "data to store" button, the parameter group of desired classification to be stored is designated, and when "store" operation is performed, the designated parameter group of the desired classification in the setting data held in the RAM is stored in the storage means.