A wind turbine for wind power generation accommodated a heat-generating device therein is always properly cooled by accurately detecting clogging of a filter. A wind turbine accommodates a heat-generating device and includes a column disposed in an upright position on a foundation, a nacelle disposed on a top end of the column, and a rotor head supported by the nacelle so as to be rotatable about a substantially horizontal axis, and the wind turbine includes an intake which is provided in an outer surface of the wind turbine and through which outside air is taken into the wind turbine to cool the heat-generating device; an exhaust which is provided in the outer surface of the wind turbine and through which air inside the wind turbine is discharged outside the wind turbine; an impurity-removing mechanism disposed in a flow path of air from the intake to the exhaust to remove impurities contained in the outside air; and a control unit for determining the condition of the impurity-removing mechanism by comparing, as a parameter serving as a criterion for determining the condition of the impurity-removing mechanism, latest data obtained while a wind speed outside the wind turbine is substantially stable with reference value data input in advance and serving as a reference.