A neutral point diode having three connecting terminals electrically commonly connected to each other is used in a type for connecting each generating coil of a three-phase alternating current electric generator for a vehicle in a Y-shape connection. The coil terminal of a neutral point side of each generating coil is connected to each of the three connecting terminals of this neutral point diode. A diode having two connecting terminals electrically commonly connected to each other is used in a type for connecting each generating coil in a .DELTA.-shape connection. The coil terminals of two adjacent generating coils are connected to the respective two connecting terminals of this diode. In both the types, one coil terminal is connected to one connecting terminal and a connecting work is simplified.