A traction transformer (10a, 10b, 10c) for installation on a vehicle, comprising: - a transformer main body, which has a winding, and is connectable to a pipe through which a refrigerant oil circulates; - an oil pump, which is configured to circulate the refrigerant oil through the pipe; - a cooler (14a, 14b), which is connectable to the pipe, and is configured to cool the refrigerant oil; characterised in that the traction transformer further comprises: - a first duct (16b, 16d), which is provided in rear of the transformer main body and the cooler (14a, 14b) in the traveling direction of the vehicle, when the traction transformer is installed on the vehicle, and includes: - a first inlet port, which is configured to take in traveling wind caused by traveling of the vehicle; - a first air blowing port, which is configured to blow the traveling wind to the cooler (14a, 14b) as cooling air; and - a first connection portion (35a, 35b), which is configured to connect the first inlet port and the first air blowing port to each other, and is configured to guide the traveling wind so that an air-blowing direction of the travelling wind is changed from a direction opposite to the traveling direction of the vehicle at the first inlet port to an opposite air-blowing direction at the first air blowing port, and to cause the guided traveling wind to be discharged as the cooling air through the first air blowing port. - a transformer main body, which has a winding, and is connectable to a pipe through which a refrigerant oil circulates; - an oil pump, which is configured to circulate the refrigerant oil through the pipe; - a cooler (14a, 14b), which is connectable to the pipe, and is configured to cool the refrigerant oil; - a first duct (16b, 16d), which is provided in rear of the transformer main body and the cooler (14a, 14b) in the traveling direction of the vehicle, when the traction transformer is installed on the vehicle, and includes: - a first inlet port, which is configured to take in traveling wind caused by traveling of the vehicle; - a first air blowing port, which is configured to blow the traveling wind to the cooler (14a, 14b) as cooling air; and - a first connection portion (35a, 35b), which is configured to connect the first inlet port and the first air blowing port to each other, and is configured to guide the traveling wind so that an air-blowing direction of the travelling wind is changed from a direction opposite to the traveling direction of the vehicle at the first inlet port to an opposite air-blowing direction at the first air blowing port, and to cause the guided traveling wind to be discharged as the cooling air through the first air blowing port. - a first inlet port, which is configured to take in traveling wind caused by traveling of the vehicle; - a first air blowing port, which is configured to blow the traveling wind to the cooler (14a, 14b) as cooling air; and - a first connection portion (35a, 35b), which is configured to connect the first inlet port and the first air blowing port to each other, and is configured to guide the traveling wind so that an air-blowing direction of the travelling wind is changed from a direction opposite to the traveling direction of the vehicle at the first inlet port to an opposite air-blowing direction at the first air blowing port, and to cause the guided traveling wind to be discharged as the cooling air through the first air blowing port.