PURPOSE: To enable to perform central ventilation for all of the rooms in each house by a single unit of ventilator, in a ventilator for a building of apartment type, by constituting an apparatus in such a manner that a feed air passage and an exhaust air passage are crossed with each other at a heat exchanger, and a ventilating fan of heat exchanger type having a vane in each passage thereof is constituted to be installed outdoors.

CONSTITUTION: The polluted air in living rooms is forcibly sucked into a heat exchanger 5 by a ventilating vane 4 from a ventilating duct 3 passing through a suction opening 2 on the room side. On the other hand, the fresh air 7 is taken into a ventilating fan 12 of heat exchanger type by vane 8 from a suction opening 7 on the outdoor side and is forcibly sucked into the heat exchanger 5. The temperature in the air taken into the heat exchanger 5 is raised in the duct 3 by giving it the heat of exhausted air from rooms and is pushed out into rooms from a feed opening 10, while the air in rooms is cooled in the duct 3 and is discharged outdoors from a discharge opening 6. With such arrangement, all of the rooms in each house can be centralizedly ventilated by a single unit of ventilator.