A keyboard apparatus includes: a plurality of keys; a plurality of hammers; a first supporting portion; a second supporting portion; an interlocking mechanism. The interlocking mechanism 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 is configured so as to maintain correspondence relations between depression speeds of the keys and moving speeds of the hammers within a range of inclinedable angles in which the keys are swingable when the front portions of the keys are depressed.