PURPOSE: To provide an axial compressor which can simply and surely prevent a rotating stall occurring near the surge limit with a high pressure ratio.

CONSTITUTION: Rib-shaped guide plates 6 with a shape following the inter-blade flow direction are provided on the inner face of a casing 1 between a train of stator blades 3 fitted on the inner face of the casing 1 in the circular passage of an industrial axial compressor or for a gas turbine. Not only the stream flowing between the stator blades 3 but also the stream flowing into a train of rotor blades 4 are corrected by the rectifying effect of the casing 1 provided with the guide plates 6, thus a rotating stall can be prevented.