PURPOSE: To accurately adjust the effect extent of a key touch, etc., and enable a superior musical instrument by switching an input information changing means for, for example, a map or arithmetic expression according to input information.

CONSTITUTION: Input information showing the input state of an input means M1 such as a key is changed by the input information changing means M2 for the map, arithmetic expression, etc., changing the effect extent of the input means M1. Namely, a change degree switching means M3 switches the input information changing means M2 according to the input information inputted by the input means M1 to adjust the degree of a change in the effect extent of the input means M1. For example, when the map is used, plural maps of touch curves for changing the input information are prepared and switched for use according to the input information on a keying speed, etc. When the arithmetic expression is used, parameters, etc., of the arithmetic expression in use are switched corresponding to the input information on, for example, the keying speed to change touch data.