PURPOSE: To easily perform key area division and tone color assignment to each key area by constituting so that setting of key area division points and tone color replacement between key areas are performed by the keyboard operation.

CONSTITUTION: A keyboard 1 generates a key on/off signal or a key code corresponding to key depression/release operation or key depression information such as touch data corresponding to the strength of key depression. At least 1st and 2nd tone colors are selected in accordance with the setting operation of a tone color operator by a tone color selecting means of a panel switch 3; and when the 1st key depression operation is performed while operating a division mode setting operator, a key area dividing means divides the keyboard with the 1st key depression position as the boundary. When a key in the key area on the higher pitched or lower pitched sound side than the 1st key depression position is depressed in the 2nd key depression operation during the 1st key depression operation, a tone color assigning means assigns either of 1st and 2nd tone colors to the key area side corresponding to this 2nd key depression position. Consequently, tone color replacement is performed by the keyboard operation.