To provide a ventilator for ventilation without increasing expenses for light and fuel and any limitation of installation locations, without giving any draft feeling by preventing the blocking of a heat exchanger at a low temperature and by stably recovering heat from indoor air to the fresh air, and without causing condensation.

The ventilator 1 comprises: a multiblade fan 12 (blowing means) for sucking the fresh air OA; a multiblade fan 13 (blowing means) for sucking indoor air RA at a normal temperature; and a heat exchanger 20 for performing heat exchange between both parties by bringing the fresh air OA into contact with the indoor air RA via a partition. In the ventilator 1, at least a partial length in a passage for indoor air in the heat exchanger 1 is set longer than at least one portion of the passage for the fresh air, and the indoor air RA is discharged from the heat exchanger 2 before at least one portion of the indoor air RA is cooled to a dew point by the fresh air OA.