A plurality of key switches (100) are arranged in two dimensions along X- and Y-coordinate axes, and an X-coordinate position of each of the key switches is associated with tone generation timing while a Y-coordinate position of each of the key switches is associated with a tone pitch. Storage section (4) stores a music piece data set that includes tone generating data having data of tone pitchesand tone generation timing associated with the key switches. In a repeat-section setting mode, a repeat-section setting section (22D, 2, 12) causes the plurality of key switches to function as setting operators and sets a repeat section of the music piece data set on the basis of the X-coordinate position of any operated one of the key switches. In reproduction of the stored music piece data set,a reproduction section repetitively reproduces the tone generating data of the music piece data set which are included in the set repeat section.Plural key switches are arranged in two dimensions along X- and Y-coordinate axes, and an X-coordinate position of each of the key switches is associated with tone generation timing while a Y-coordinate position of each of the key switches is associated with a tone pitch. Storage section stores a music piece data set that includes tone generating data having data of tone pitches and tone generation timing associated with the key switches. In a repeat-section setting mode, a repeat-section setting section causes the plural key switches to function as setting operators and sets a repeat section of the music piece data set on the basis of the X-coordinate position of any operated one of the key switches. In reproduction of the stored music piece data set, a reproduction section repetitively reproduces the tone generating data of the music piece data set which are included in the set repeat section.