To provide a diesel locomotive capable of optimizing combustion temperature in a diesel engine and reducing NOx in exhaust gas.

A radiator 31 for cooling engine cooling water is provided on the front face of a distal end part of a bonnet 12 housing the diesel engine and an intake air cooling water cooler 32 for cooling intake air cooling water for cooling combustion air compressed by a supercharger with an intake air cooler is provided on a side face of the distal end part. A fan 33 common to the radiator and the intake air cooling water cooler is provided on a back side of the radiator, and an oil cooler 19 for cooling the operating oil of a hydraulic transmission with the cooling water and a fuel cooler 35 for cooling the fuel supplied to the diesel engine are provided.