A keyboard apparatus includes: keys composed of white keys and black keys supported pivotably on a key mounting part of a frame; mass members pivotably supported on a mass member mounting part and driven by mass member driving parts provided underside of the keys; and a mass member lower limit stopper and a mass member upper limit stopper restricting a pivot range of the mass members. Each of the mass members includes a mass concentration part. The mass concentration part extends more outward in a key longitudinal direction than a position where the mass member upper limit stopper on the frame is disposed, and an upper face of the mass concentration part at its highest lifted position is substantially flush with an upper face of a rear end portion of the white key main body.