An AC power generator, comprising: a rotor rotatably supported in a casing, wherein a shaft is rotatably supported on the casing and the rotor is fixed to the shaft; a stator having a stator winding wire and supported on the casing; a pair of slip rings fixed to the extending portion of the shaft extending toward the rear side of the casing; a rectifying device (20, 220) disposed around the shaft on a plane orthogonal to the shaft core of the shaft outside the peripheries of the slip rings, the rectifying device (20,220) being configured to rectify an AC current generated in the stator winding wire; a brush holder located outside the peripheries of the pair of slip rings and disposed between tips of the rectifying device; a voltage adjuster attached to the brush holder and configured to adjust a magnitude of an AC voltage generated in the stator, the rectifying device (20, 220) including positive and negative side C-shaped heat sinks (22, 26) supporting rectifying elements (24, 28) and configured to cool the rectifying elements (24, 28) and a circuit board holding the heat sinks (22, 26), the heat sinks (22, 26) and the circuit board being stacked, the circuit board including engaging projections (34, 35), and the heat sinks (22, 26) including holes (23, 27), into which the engaging projections (34, 35) are fit, characterised by further comprising a gravity center adjustment portion (29, 229), wherein the gravity center adjustment portion (29, 229) has the same thickness as the thickness of the portion of the heat sinks (22, 26) with the holes (23, 27), wherein the thickness direction is the direction in which the circuit board and the heat sinks (22, 26) are stacked, and the gravity center adjustment portion (29,229) is provided at positions around both tip portions of the C-shape for inhibiting the inclination of the heat sinks (22,26) when the heat sinks (22,26) are stacked. a rotor rotatably supported in a casing, wherein a shaft is rotatably supported on the casing and the rotor is fixed to the shaft; a stator having a stator winding wire and supported on the casing; a pair of slip rings fixed to the extending portion of the shaft extending toward the rear side of the casing; a rectifying device (20, 220) disposed around the shaft on a plane orthogonal to the shaft core of the shaft outside the peripheries of the slip rings, the rectifying device (20,220) being configured to rectify an AC current generated in the stator winding wire; a brush holder located outside the peripheries of the pair of slip rings and disposed between tips of the rectifying device; a voltage adjuster attached to the brush holder and configured to adjust a magnitude of an AC voltage generated in the stator, the rectifying device (20, 220) including positive and negative side C-shaped heat sinks (22, 26) supporting rectifying elements (24, 28) and configured to cool the rectifying elements (24, 28) and a circuit board holding the heat sinks (22, 26), the heat sinks (22, 26) and the circuit board being stacked, the circuit board including engaging projections (34, 35), and the heat sinks (22, 26) including holes (23, 27), into which the engaging projections (34, 35) are fit, characterised by further comprising a gravity center adjustment portion (29, 229), wherein the gravity center adjustment portion (29, 229) has the same thickness as the thickness of the portion of the heat sinks (22, 26) with the holes (23, 27), wherein the thickness direction is the direction in which the circuit board and the heat sinks (22, 26) are stacked, and the gravity center adjustment portion (29,229) is provided at positions around both tip portions of the C-shape for inhibiting the inclination of the heat sinks (22,26) when the heat sinks (22,26) are stacked.