PURPOSE: To provide a heat exchange ventilator which is excellent in sound insulation and protectivity against ingress of cool air by providing a heat exchange element for transmitting the heat of warm air to cool air between a duct used as a passage for cool air and a duct used as a passage for warm air and making both ducts flexible.

CONSTITUTION: When fans 16 and 17 are rotated, outdoor air (cool air) passes through an air supply duct 13 and enters within the chamber, and, at the same time, passes through an exhaust duct 14 and air within the chamber (warmed air) is exhausted out of the house thereby to carry out indoor ventilation. Upon this occasion, a heat exchange is carried out between supply air and exhaust air by a heat exchange element 19, and the temperature of supply air becomes close to the indoor temperature, thus the room temperature change due to the ventilation and heat loss being small. At the time of cooling in summer season, fans 16 and 17 are rotated reversely, the duct 14 is used as a supply air passage (warm air passage) and the duct 13 is used as an exhaust air passage (cool air passage). Since the ducts are flexible, they are properly bent and even a long duct can be accommodated in a narrow space and long supply air and exhaust air passages can be provided whereby it is possible to reduce the quantities of noise and cool air.