A drive device for a railway vehicle, the drive device comprising: a first electric power converting device formed by a switching element to convert DC electric power into AC electric power and supply the AC electric power to a load; a control device for controlling the first electric power converting device; and a first cooler using a liquid as a coolant for cooling the first electric power converting device; wherein the first cooler includes a heat receiving portion in contact with the switching element, the heat receiving portion absorbing heat of the switching element, a heat receiving portion temperature sensor for measuring a temperature of the heat receiving portion, a heat radiating portion for radiating the heat absorbed from the switching element, and a heat radiating portion temperature sensor for measuring a temperature of the heat radiating portion, and the control device includes an arithmetic section for determining whether the coolant is frozen from a magnitude of a thermal resistance value of the first cooler, the magnitude of the thermal resistance value of the first cooler being calculated using the detected respective measured values of the heat receiving portion temperature sensor and the heat radiating portion temperature sensor, the measured values being detected by feeding a predetermined current through the switching element, and an amount of heat generated by the switching element or an energizing current value corresponding to the amount of heat generated by the switching element, when at least one of the respective measured values of the heat receiving portion temperature sensor and the heat radiating portion temperature sensor becomes equal to or lower than a melting point of the coolant. a first electric power converting device formed by a switching element to convert DC electric power into AC electric power and supply the AC electric power to a load; a control device for controlling the first electric power converting device; and a first cooler using a liquid as a coolant for cooling the first electric power converting device; wherein the first cooler includes a heat receiving portion in contact with the switching element, the heat receiving portion absorbing heat of the switching element, a heat receiving portion temperature sensor for measuring a temperature of the heat receiving portion, a heat radiating portion for radiating the heat absorbed from the switching element, and a heat radiating portion temperature sensor for measuring a temperature of the heat radiating portion, and a heat receiving portion in contact with the switching element, the heat receiving portion absorbing heat of the switching element, a heat receiving portion temperature sensor for measuring a temperature of the heat receiving portion, a heat radiating portion for radiating the heat absorbed from the switching element, and a heat radiating portion temperature sensor for measuring a temperature of the heat radiating portion, and the control device includes an arithmetic section for determining whether the coolant is frozen from a magnitude of a thermal resistance value of the first cooler, the magnitude of the thermal resistance value of the first cooler being calculated using the detected respective measured values of the heat receiving portion temperature sensor and the heat radiating portion temperature sensor, the measured values being detected by feeding a predetermined current through the switching element, and an amount of heat generated by the switching element or an energizing current value corresponding to the amount of heat generated by the switching element, when at least one of the respective measured values of the heat receiving portion temperature sensor and the heat radiating portion temperature sensor becomes equal to or lower than a melting point of the coolant.