A heat exchange type ventilator allows preventing its heat exchanger from being clogged with buildup of ice, and also alleviating cold-draft feeling. This ventilator has an exhaust-air coupling section and a supply-air coupling section, and a ventilating unit which includes an exhaust-air outlet and a supply-air inlet, a motor for driving an exhaust-air fan and a supply-air fan, the heat exchanger for carrying out heat recovery between interior air and outside air, and a cut-off damper for cutting off a supply-air flow in a supply-air channel. Supply-air temperature sensing means for sensing a temperature of the outside air issues a signal, which prompts the damper to cut off the supply-air flow and reduce a volume of the exhaust-air.