To provide a power generation controller for a vehicle having automatic transmission which can suppress temperature rise of automatic transmission fluid and avoid deterioration thereof.

A manual power generation switch 12 for changeover to an exclusive power generation mode is provided. In an exclusive power generation mode, a temperature Tatf of automatic transmission fluid is measured by a fluid temperature sensor 19, and if the measured value exceeds a predetermined threshold Temp1, an ECU 8 inhibits supplying of power to the outside. With this constitution, an engine 1 will not be driven for the power supply to the outside and the automatic transmission will not rotate any longes with the engine 1, so that the temperature rise of the automatic transmission fluid can be suppressed.