A ventilator comprising: a heat exchanger including a plurality of layered partition members, and having an exhaust air flow inlet face that faces a direction perpendicular to a layering direction of the partition members and through which an exhaust air flow enters, an exhaust air flow outlet face that faces a direction perpendicular to the layering direction of the partition members and through which the exhaust air flow exits, a supply air flow inlet face that faces a direction perpendicular to the layering direction of the partition members and through which a supply air flow enters, and a supply air flow outlet face that faces a direction perpendicular to the layering direction of the partition members and through which the supply air flow exits; and a housing accommodating the heat exchanger therein, and including a first end wall part covering a first end side of the heat exchanger along the layering direction, and a second end wall part covering a second end side of the heat exchanger along the layering direction, wherein the inside of the housing is partitioned into an exhaust air flow inlet space to which the exhaust air flow inlet face is exposed, an exhaust air flow outlet space to which the exhaust air flow outlet face is exposed, a supply air flow inlet space to which the supply air flow inlet face is exposed, and a supply air flow outlet space to which the supply air flow outlet face is exposed, the first end wall part has a first opening communicating with the exhaust air flow inlet space, a second opening communicating with the exhaust air flow outlet space, a third opening communicating with the supply air flow inlet space, and a fourth opening communicating with the supply air flow outlet space, and the housing has a fifth opening communicating with the exhaust air flow outlet space, and a sixth opening communicating with the supply air flow inlet space characterized in that the ventilator further comprises: a first damper to selectively close either one of the first opening and the third opening; and a second damper to selectively close either one of the second opening and the fourth opening. a heat exchanger including a plurality of layered partition members, and having an exhaust air flow inlet face that faces a direction perpendicular to a layering direction of the partition members and through which an exhaust air flow enters, an exhaust air flow outlet face that faces a direction perpendicular to the layering direction of the partition members and through which the exhaust air flow exits, a supply air flow inlet face that faces a direction perpendicular to the layering direction of the partition members and through which a supply air flow enters, and a supply air flow outlet face that faces a direction perpendicular to the layering direction of the partition members and through which the supply air flow exits; and a housing accommodating the heat exchanger therein, and including a first end wall part covering a first end side of the heat exchanger along the layering direction, and a second end wall part covering a second end side of the heat exchanger along the layering direction, wherein the inside of the housing is partitioned into an exhaust air flow inlet space to which the exhaust air flow inlet face is exposed, an exhaust air flow outlet space to which the exhaust air flow outlet face is exposed, a supply air flow inlet space to which the supply air flow inlet face is exposed, and a supply air flow outlet space to which the supply air flow outlet face is exposed, the first end wall part has a first opening communicating with the exhaust air flow inlet space, a second opening communicating with the exhaust air flow outlet space, a third opening communicating with the supply air flow inlet space, and a fourth opening communicating with the supply air flow outlet space, and the housing has a fifth opening communicating with the exhaust air flow outlet space, and a sixth opening communicating with the supply air flow inlet space characterized in that the ventilator further comprises: a first damper to selectively close either one of the first opening and the third opening; and a second damper to selectively close either one of the second opening and the fourth opening. a first damper to selectively close either one of the first opening and the third opening; and a second damper to selectively close either one of the second opening and the fourth opening.