A work vehicle comprising: an engine ; a radiator that cools a refrigerant of the engine ; a hydraulic pump that is driven by the engine ; a refrigerant temperature sensor that detects a temperature (TW) of the refrigerant; an outside air temperature sensor that detects a temperature (TA) of an outside air; a thermostat that opens and closes a flowpath between a fully closed state and a fully opened state in accordance with the temperature (TW) of the refrigerant on the flowpath for supplying the refrigerant to the radiator ; a hydraulic motor which is driven by a pressure oil delivered from the hydraulic pump , and rotates a cooling fan for blowing a cooling air to the radiator ; a directional control valve that switches the flow direction of the pressure oil from the hydraulic pump to rotate the hydraulic motor in forward and reverse directions; and a control device that controls the directional control valve to cause the repetitive operation of the forward and reverse rotation of the cooling fan to be performed at predetermined time intervals (TS), wherein the control device changes setting of the time intervals (TS) when a relationship between the outside air temperature (TA) detected by the outside air temperature sensor and the refrigerant temperature (TW) detected by the refrigerant temperature sensor satisfies a predetermined condition defined in advance, characterized in that the predetermined condition includes a high temperature condition in which the outside air temperature (TA) detected by the outside air temperature sensor is higher than a reference value, and a low temperature condition in which the outside air temperature (TA) is lower than the reference value, and the control device reduces the time interval (TS) more than a normal time (TS1) initially set when the refrigerant temperature (TW) detected from the refrigerant temperature sensor reaches a first set temperature (TW1) under the low temperature condition or when the refrigerant temperature (TW) detected from the refrigerant temperature sensor reaches a second set temperature (TW2) higher than the first set temperature (TW1) under the high temperature condition. wherein the control device changes setting of the time intervals (TS) when a relationship between the outside air temperature (TA) detected by the outside air temperature sensor and the refrigerant temperature (TW) detected by the refrigerant temperature sensor satisfies a predetermined condition defined in advance, characterized in that the predetermined condition includes a high temperature condition in which the outside air temperature (TA) detected by the outside air temperature sensor is higher than a reference value, and a low temperature condition in which the outside air temperature (TA) is lower than the reference value, and the control device reduces the time interval (TS) more than a normal time (TS1) initially set when the refrigerant temperature (TW) detected from the refrigerant temperature sensor reaches a first set temperature (TW1) under the low temperature condition or when the refrigerant temperature (TW) detected from the refrigerant temperature sensor reaches a second set temperature (TW2) higher than the first set temperature (TW1) under the high temperature condition. <EOS>