An automotive rotary electric machine comprising: a rotor that is disposed inside a casing so as to be fixed to a shaft that is rotatably supported by said casing; a stator comprising: a stator core; and a stator winding that is mounted onto said stator core, said stator being supported by said casing so as to surround said rotor; a rectifier that rectifies alternating-current electric power that is generated by said stator winding, said rectifier forming a C shape, and being fixed to said casing so as to be disposed outside a first axial end of said casing in a fan shape that is centered around said shaft in a plane that is perpendicular to said shaft; a voltage regulator that adjusts magnitude of an alternating-current voltage that is generated by said stator, said voltage regulator being disposed outside said first axial end of said casing between two circumferential end portions of said C shape of said rectifier; and a resin protective cover that is formed so as to have a cup shape that is constituted by a bottom portion and a tubular peripheral wall portion, and that is mounted to said casing so as to cover said rectifier and said voltage regulator, said rectifier comprising a circuit board that comprises: a resin-molded body that is formed so as to have a C shape; a plurality of conductors that are insert-molded into said resin-molded body so as to connect rectifying elements so as to configure a diode bridge; characterized in that said rectifier comprises a plurality of projection-engaging portions that are formed on an outer peripheral wall surface of said resin-molded body so as to be separated circumferentially; and in that said protective cover comprises a plurality of projections that are disposed so as to protrude from an inner circumferential wall surface of said peripheral wall portion so as to align with said projection-engaging portions, and is held on said casing by means of said circuit board by coupling said projections to said projection-engaging portions by snap-fitting using elasticity of said peripheral wall portion. a rotor that is disposed inside a casing so as to be fixed to a shaft that is rotatably supported by said casing; a stator comprising: a stator core; and a stator winding that is mounted onto said stator core, said stator being supported by said casing so as to surround said rotor; a stator core; and a stator winding that is mounted onto said stator core, said stator being supported by said casing so as to surround said rotor; a rectifier that rectifies alternating-current electric power that is generated by said stator winding, said rectifier forming a C shape, and being fixed to said casing so as to be disposed outside a first axial end of said casing in a fan shape that is centered around said shaft in a plane that is perpendicular to said shaft; a voltage regulator that adjusts magnitude of an alternating-current voltage that is generated by said stator, said voltage regulator being disposed outside said first axial end of said casing between two circumferential end portions of said C shape of said rectifier; and a resin protective cover that is formed so as to have a cup shape that is constituted by a bottom portion and a tubular peripheral wall portion, and that is mounted to said casing so as to cover said rectifier and said voltage regulator, said rectifier comprising a circuit board that comprises: a resin-molded body that is formed so as to have a C shape; a plurality of conductors that are insert-molded into said resin-molded body so as to connect rectifying elements so as to configure a diode bridge; characterized in that said rectifier comprises a plurality of projection-engaging portions that are formed on an outer peripheral wall surface of said resin-molded body so as to be separated circumferentially; and in that a resin-molded body that is formed so as to have a C shape; a plurality of conductors that are insert-molded into said resin-molded body so as to connect rectifying elements so as to configure a diode bridge; characterized in that said rectifier comprises a plurality of projection-engaging portions that are formed on an outer peripheral wall surface of said resin-molded body so as to be separated circumferentially; and in that said protective cover comprises a plurality of projections that are disposed so as to protrude from an inner circumferential wall surface of said peripheral wall portion so as to align with said projection-engaging portions, and is held on said casing by means of said circuit board by coupling said projections to said projection-engaging portions by snap-fitting using elasticity of said peripheral wall portion.