A synchronous reluctance motor comprising: a rotor shaft which is supported in a rotatable manner and axially extends at a rotation axis; a rotor core shaped in a cylindrical form including a bridge portion on an outer peripheral portion thereof, on which a plurality of flux barriers (31, 32, 41, 42) are formed and which is disposed on the outer circumference of the rotor shaft and fixed to the rotor shaft and extends in the direction of the rotation axis; a stator core which is disposed on an outer periphery of the rotor core in such a way as to form a gap between the rotor core and the stator core and on which a plurality of protruding stator teeth are formed in such a way as to be spaced out in a circumferential direction each other and extend in the direction of the rotation-axis; and multiphase armature windings of a plurality of poles which are wound around the plurality of stator teeth, wherein the flux barriers (31, 32, 41, 42) include a plurality of first flux barriers (41, 42) which are formed in such a way as to be spaced out in the circumferential direction each other and extend in a radial direction, and a plurality of second flux barriers (31, 32) which are formed in each of circumferential angular regions sandwiched between the first flux barriers (41, 42) in such a way as to form a curved surface protruding toward the center of the rotation-axis and to spread and be mutually spaced out in the circumferential direction, characterized in that the rotor shaft includes a plurality of radial plates which are made of nonmagnetic material and spaced out in the circumferential direction and which extend toward a radial-direction outer side and extend in the direction of the rotation-axis and are disposed in the first flux barriers (41, 42), and projections are formed at least in one of the rotor core and the radial plates and grooves are formed in another for mutual fitting. a rotor shaft which is supported in a rotatable manner and axially extends at a rotation axis; a rotor core shaped in a cylindrical form including a bridge portion on an outer peripheral portion thereof, on which a plurality of flux barriers (31, 32, 41, 42) are formed and which is disposed on the outer circumference of the rotor shaft and fixed to the rotor shaft and extends in the direction of the rotation axis; a stator core which is disposed on an outer periphery of the rotor core in such a way as to form a gap between the rotor core and the stator core and on which a plurality of protruding stator teeth are formed in such a way as to be spaced out in a circumferential direction each other and extend in the direction of the rotation-axis; and multiphase armature windings of a plurality of poles which are wound around the plurality of stator teeth, wherein the flux barriers (31, 32, 41, 42) include a plurality of first flux barriers (41, 42) which are formed in such a way as to be spaced out in the circumferential direction each other and extend in a radial direction, and a plurality of second flux barriers (31, 32) which are formed in each of circumferential angular regions sandwiched between the first flux barriers (41, 42) in such a way as to form a curved surface protruding toward the center of the rotation-axis and to spread and be mutually spaced out in the circumferential direction, a plurality of first flux barriers (41, 42) which are formed in such a way as to be spaced out in the circumferential direction each other and extend in a radial direction, and a plurality of second flux barriers (31, 32) which are formed in each of circumferential angular regions sandwiched between the first flux barriers (41, 42) in such a way as to form a curved surface protruding toward the center of the rotation-axis and to spread and be mutually spaced out in the circumferential direction, characterized in that the rotor shaft includes a plurality of radial plates which are made of nonmagnetic material and spaced out in the circumferential direction and which extend toward a radial-direction outer side and extend in the direction of the rotation-axis and are disposed in the first flux barriers (41, 42), and projections are formed at least in one of the rotor core and the radial plates and grooves are formed in another for mutual fitting.