a plurality of keys;

a plurality of hammers respectively associated with the keys such that each hammer applies a load to a respective key;

a first supporting portion that supports the keys such that front portions of the keys are swingable in an up-and-down direction;

a second supporting portion that supports the hammers above the keys such that the hammers are movable in the up-and-down direction;

an interlocking mechanism that conveys weight of the hammers respectively to rear portions of the keys, and causes an upward movement of the hammers, when front portions of the keys are depressed and the rear portions of the keys are swung upward, the interlocking mechanism includes a plurality of adjustment screws respectively associated with the plurality of the hammers, each of the adjustment screws includes a connecting end portion and a slidable end portion;

the connecting end portion is connected to one of a bottom surface of one of the hammers and a top surface of the rear portion of one of the keys;

the slidable end portion includes at least one curved surface that at least partially abuts and slides on the other of the bottom surface of one of the hammers and the top surface of the rear portion of one of the keys so as to maintain correspondence relations between depression speeds of one of the keys and moving speeds of one of the hammers; and

the at least one curved surface of the slidable end portion slides on the other of the bottom surface of one of the hammers and the top surface of the rear portion of one of the keys within a range of inclined angles in which the keys are swingable when the front portions of the keys are depressed.