A keyboard apparatus capable of being easily designed to have action units whose upper end positions are made low and whose efficiency of drive of whippens is increased. Each of keys of the keyboard apparatus has an upper front part, a bent part extending downward from a rear end of the upper front part, and a lower rear part extending rearward from a lower end of the bent part. An upper surface of a rear end portion of the lower rear part nearly horizontally extends at a height position lower than that of a key fulcrum. Action units are disposed above respective ones of rear end portions of the keys. A driven point of a whippen of each action unit is located at a position lower than the key fulcrum in a non-key-depression state.