An axial compressor includes: a rotor as a rotational shaft, rotor blades mounted on the rotor, a compressor casing that covers the rotor and the rotor blades, and stator vanes mounted on the compressor casing. The rotor blades and the stator vanes are each disposed in a circumferential direction of the rotational shaft to form a rotor-blade cascade and a stator-vane cascade, respectively. The rotor-blade cascade and the stator-vane cascade are arranged in plural rows, respectively, in an axial direction of the rotational shaft. The stator vane has a dovetail, and the compressor casing has a dovetail groove that extends in the circumferential direction of the rotational shaft to receive the dovetail inserted therein to fix the stator vanes. Two or more stator vanes, the stator vanes belonging to stator-vane cascades different from each other, are fixed in the dovetail groove.