Abstract: An axial flow device includes: at least one stage of a compressor including a rotor blade row and a stator vane row; a casing housing the compressor; and an operating range expansion unit having a suction port that opens into a region corresponding to the rotor blade row in an inner surface of the casing, a blow-out port that opens anterior to the rotor blade row in the inner surface of the casing, and a hollow section that is formed inside the casing and communicates the suction port with the blow-out port. A flow path in the blow-out port is inclined reversely to a rotation direction of the rotor blade row relative to the radially inward side.