A keyboard apparatus in which the radius of turning motion of a mainly operated portion of each black key in a key depressing/releasing direction is maximized so as to enhance the operability of the black key for performance. The keyboard apparatus has a key frame formed with fixing parts. In the key frame, there are arranged a plurality of key units each having a plurality of white keys and a plurality of black keys integrally connected to a common base end part held by the fixing parts of the key frame. Each of the white keys and the black keys comprises a base end part, a key main body, and a hinge part connecting the key main body to the base end part such that the key main body is swingable about the base end part in the key depressing/releasing direction, and the hinge part of each of the black keys is located rearward of the hinge part of each of the white keys.