In order to improve a touch of a key of a keyboard musical instrument by using a key actuating apparatus which actuates the key supported so as to be rotationally movable with regard to a frame of the keyboard musical apparatus, a key actuating apparatus (1) includes: a plunger (15) which is moved on an arc or curved line in correspondence with a rotational motion of a key (3); and a solenoid (7) including electro magnets (17 and 19) which are fixed to the frame and which are substantially in a cylindrical shape into which the plunger is inserted. The plunger (15) is formed in an arc or curved shape extended in a direction of a rotational motion of the plunger (15). A head end (15b) arranged on the plunger (15) in a lengthwise direction is made from a magnetic body.