A synthesizer 10 is configured such that when a PC 30 is connected thereto, the synthesizer 10 accepts selection of a tone used for sound generation from among a tone included in an internal tone generation unit 16 and a tone included in a tone generation module 312 provided by the external PC 30, and causes the PC 30 to enable the function of the tone generation module 312, downloads an edit operation accepting program corresponding to the tone generation module 312 from a UI control program memory 315 of the PC 30, and executes the downloaded edit operation accepting program to thereby realize a function of editing data of the tone included in the tone generation module 312, the data being stored in the PC 30, when the tone included in the tone generation module 312 of the PC 30 is selected.