A keyboard apparatus includes: keys; at least one frame configured to support at least one of the keys; at least one bendable portion disposed between one of the keys and the frame and having flexibility in a scale direction; and a coupler configured to couple the bendable portion and the key to each other attachably and detachably. Two couplers each as the coupler which correspond respectively to the keys adjacent to each other are disposed respectively at positions different from each other in a longitudinal direction of the key.