An axial compressor comprising: a casing having a tubular shape; variable stator vanes each having a vane shaft as a swing center, provided in the casing as stator vanes or inlet guide vanes, and arranged in a circumferential direction of the casing; rotor blades provided on a trailing edges side of the variable stator vanes in the casing and arranged in the circumferential direction of the casing; characterized in that the axial compressor further comprises: a plasma actuator configured to generate a plasma annularly distributed in the circumferential direction of the casing, the plasma actuator being attached on an inner circumferential surface of the casing and intersecting with a clearance between each variable stator vane and the inner circumferential surface of the casing; wherein the plasma actuator is located in an axial direction of the casing in a first region between the vane shafts and trailing edges of the variable stator vanes in a fully-closed state and in a second region between the trailing edges of the variable stator vanes in the fully-closed state and the trailing edges of the variable stator vanes in a fully-opened state, and wherein the axial compressor is configured such that a generation of the plasma in the second region by the plasma actuator is controlled depending on an opening degree of the variable stator vanes. a casing having a tubular shape; variable stator vanes each having a vane shaft as a swing center, provided in the casing as stator vanes or inlet guide vanes, and arranged in a circumferential direction of the casing; rotor blades provided on a trailing edges side of the variable stator vanes in the casing and arranged in the circumferential direction of the casing; characterized in that the axial compressor further comprises: a plasma actuator configured to generate a plasma annularly distributed in the circumferential direction of the casing, the plasma actuator being attached on an inner circumferential surface of the casing and intersecting with a clearance between each variable stator vane and the inner circumferential surface of the casing; wherein the plasma actuator is located in an axial direction of the casing in a first region between the vane shafts and trailing edges of the variable stator vanes in a fully-closed state and in a second region between the trailing edges of the variable stator vanes in the fully-closed state and the trailing edges of the variable stator vanes in a fully-opened state, and wherein the axial compressor is configured such that a generation of the plasma in the second region by the plasma actuator is controlled depending on an opening degree of the variable stator vanes. a plasma actuator configured to generate a plasma annularly distributed in the circumferential direction of the casing, the plasma actuator being attached on an inner circumferential surface of the casing and intersecting with a clearance between each variable stator vane and the inner circumferential surface of the casing; wherein the plasma actuator is located in an axial direction of the casing in a first region between the vane shafts and trailing edges of the variable stator vanes in a fully-closed state and in a second region between the trailing edges of the variable stator vanes in the fully-closed state and the trailing edges of the variable stator vanes in a fully-opened state, and wherein the axial compressor is configured such that a generation of the plasma in the second region by the plasma actuator is controlled depending on an opening degree of the variable stator vanes.