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.