An alternator includes a rotor for forming north-seeking (N) and south-seeking (S) poles about a rotational circumference, a stator including a stator core disposed facing the rotor, and a stator winding installed in the stator core, a bracket supporting the rotor and the stator, and a cooling means for cooling the stator winding by moving together with the rotor and generating a flow of cooling air inside the bracket, wherein the stator core includes a laminated core formed with a number of slots extending axially at a predetermined pitch in a circumferential direction, the stator winding includes a number of winding sub-portions in each of which a long strand of wire is wound so as to alternately occupy an inner layer and an outer layer in a slot depth direction within the slots at intervals of a predetermined number of slots, the strand of wire folding back outside the slots at first and second axial end surfaces of the stator core to form turn portions, the turn portions align in a circumferential direction to constitute coil ends, an electrically-insulative resin portion is disposed so as to completely cover the coil ends, and at least one surface of the electrically-insulative resin portion selected from a rotor-facing surface and a bracket-facing surface is formed into a smooth surface.