A rotating electrical machine for a vehicle, comprising: a rotor rotatably supported in a casing; a stator comprising a stator core and a stator coil wound around the stator core, the stator being supported by the casing so as to surround the rotor; a rectifier comprising a positive-electrode side heat sink having positive-electrode side rectifying elements mounted therein, for rectifying AC power generated in the stator coil, the rectifier being arranged outside the casing at a position on one side in an axial direction; a protective cover made of a resin into a bottomed cylindrical shape including a bottom portion having a through hole formed therein and a cylindrical circumferential wall portion, the protective cover comprising a protruding portion projected in an opening direction from a circumferential edge portion of the through hole, the protective cover being mounted to the casing so as to cover the rectifier; a fixing bolt that is inserted into the through hole and is firmly fixed to the casing at the position on the one side in the axial direction, for fixing the rectifier to the casing; an insulating member comprising a projecting portion projected toward the protective cover, for electrically insulating the fixing bolt and the positive-electrode side heat sink from each other; a fitting firmly fixed to an extending portion of the fixing bolt that extends from the through hole; and a harness clamp made of a resin, for fixing an electric wire, wherein the harness clamp is held by the fitting, and wherein the projecting portion and the protruding portion are arranged at a position so that the projecting portion and the protruding portion are overlapped with each other in the axial direction of the fixing bolt. a rotor rotatably supported in a casing; a stator comprising a stator core and a stator coil wound around the stator core, the stator being supported by the casing so as to surround the rotor; a rectifier comprising a positive-electrode side heat sink having positive-electrode side rectifying elements mounted therein, for rectifying AC power generated in the stator coil, the rectifier being arranged outside the casing at a position on one side in an axial direction; a protective cover made of a resin into a bottomed cylindrical shape including a bottom portion having a through hole formed therein and a cylindrical circumferential wall portion, the protective cover comprising a protruding portion projected in an opening direction from a circumferential edge portion of the through hole, the protective cover being mounted to the casing so as to cover the rectifier; a fixing bolt that is inserted into the through hole and is firmly fixed to the casing at the position on the one side in the axial direction, for fixing the rectifier to the casing; an insulating member comprising a projecting portion projected toward the protective cover, for electrically insulating the fixing bolt and the positive-electrode side heat sink from each other; a fitting firmly fixed to an extending portion of the fixing bolt that extends from the through hole; and a harness clamp made of a resin, for fixing an electric wire, wherein the harness clamp is held by the fitting, and