A work machine, comprising: an engine; a radiator for cooling a cooling water of the engine; a thermostat, provided upon a path that conducts the cooling water to the radiator, and that opens and closes the path between fully closed and fully open according to a temperature of the cooling water; a fan device (11, 13) that blows external air at the radiator; a rotational speed setting unit that sets a rotational speed for the fan device (11, 13) according to the temperature of the cooling water; and a rotational speed adjustment unit that adjusts rotational speed of the fan device (11, 13) so that it becomes equal to the rotational speed set by the rotational speed setting unit, characterised in that: an engine output mode changeover switch is provided, with which an operator selects either a P mode in which output of the engine is not limited, or an E mode in which during light load the output of the engine is limited in such a way that the highest rotational speed of the engine or the output torque of the engine is limited, and in that: within a temperature range for the cooling water in which the thermostat is fully opened from fully closed, the rotational speed setting unit sets the rotational speed of the fan device (11, 13) to be lower when the engine output mode changeover switch is changed over so that the output of the engine is limited, as compared to when the engine output mode changeover switch is changed over so that the output of the engine is not limited. an engine; a radiator for cooling a cooling water of the engine; a thermostat, provided upon a path that conducts the cooling water to the radiator, and that opens and closes the path between fully closed and fully open according to a temperature of the cooling water; a fan device (11, 13) that blows external air at the radiator; a rotational speed setting unit that sets a rotational speed for the fan device (11, 13) according to the temperature of the cooling water; and a rotational speed adjustment unit that adjusts rotational speed of the fan device (11, 13) so that it becomes equal to the rotational speed set by the rotational speed setting unit, characterised in that: an engine output mode changeover switch is provided, with which an operator selects either a P mode in which output of the engine is not limited, or an E mode in which during light load the output of the engine is limited in such a way that the highest rotational speed of the engine or the output torque of the engine is limited, and in that: within a temperature range for the cooling water in which the thermostat is fully opened from fully closed, the rotational speed setting unit sets the rotational speed of the fan device (11, 13) to be lower when the engine output mode changeover switch is changed over so that the output of the engine is limited, as compared to when the engine output mode changeover switch is changed over so that the output of the engine is not limited. an engine output mode changeover switch is provided, with which an operator selects either a P mode in which output of the engine is not limited, or an E mode in which during light load the output of the engine is limited in such a way that the highest rotational speed of the engine or the output torque of the engine is limited, and in that: within a temperature range for the cooling water in which the thermostat is fully opened from fully closed, the rotational speed setting unit sets the rotational speed of the fan device (11, 13) to be lower when the engine output mode changeover switch is changed over so that the output of the engine is limited, as compared to when the engine output mode changeover switch is changed over so that the output of the engine is not limited. within a temperature range for the cooling water in which the thermostat is fully opened from fully closed, the rotational speed setting unit sets the rotational speed of the fan device (11, 13) to be lower when the engine output mode changeover switch is changed over so that the output of the engine is limited, as compared to when the engine output mode changeover switch is changed over so that the output of the engine is not limited.