PURPOSE: To reduce plugging of a filter, to decrease necessary power of a fan by continuous removal of collected dust and to reduce maintenance and inspection as much as possible.

CONSTITUTION: An outside air duct in which the outside air flows and an exhaust duct 3 for discharging exhaust gas (d) are provided on the outdoor side of a rotor 1 for containing a honeycomb type heat exchanging element group, and a circulating duct 4 for introducing circulated air (c) from a room and an air supply duct 5 for supplying the air (b) are provided inside the room. A disclike filter 6 is mounted on the outdoor side of the rotor 1 to be rotated together with a rotor 1 or independently rotated. A brush 7 for scraping off dusts adhering to the filter 6 is disposed along an upper side of a central partition plate 8 on the upstream side of the rotational direction on the blowing side of the circulating air of the filter 6. A dust discharge outlet 8a for discharging the dust is formed at the central partition of the back of the brush 7, and a duct collector 9 is disposed under it. Numeral 10 denotes a filter for collecting dusts contained in the air (c), and 1a is a sealing rubber.