In air flow paths of a swinging apparatus in which racks are respectively provided to pistons of a pair for swinging in cylinder bores of a pair disposed in parallel in a casing, a pinion is engaged with the racks, and the pistons of the pair are synchronously driven in opposite directions to each other by synchronously supplying and discharging pressure air to and from opposite ends to each other of the pistons of the pair, the air flow paths for supplying and discharging the pressure air to and from opposite ends to each other of the pistons of the pair are formed between a bottom of the casing and a flow path forming member mounted to the bottom.