A keyboard instrument includes an upper case having an upper side installation part; a lower case having a lower side installation part at a position corresponding to the upper side installation part of the upper case; a keyboard unit including a key-connecting part to which a plurality of keys are connected, the key-connecting part having an insertion hole to which at least one of the upper side installation part and the lower side installation part is inserted; and a fastening member fastening the upper side installation part and the lower side installation part together.