<;P>;PROBLEM TO BE SOLVED: To provide a ventilation structure of a hothouse solving the following problems: since stable air blasting cannot be performed in some places when a plastic hothouse has a large area and a large volume, uneven humidity and temperature are caused; crops suffer from disease; harmful insects develop; and as a result, quality crops can not be harvested, so that efficient cultivation in the hothouse is not performed. <;P>;SOLUTION: The ventilation structure of a hothouse includes a double curtain covering the inside of an outer-stretch curtain stretched over a ceiling surface, wire members supporting the double curtain and longitudinally installed from one flank surface, a fixing means fixing the double curtain with the wire members, a rotating bar set to the opening end part of the double curtain to function as an air gateway, and a blower provided with a blowing pipe blowing the wind to the vicinity of the rotating bar. <;P>;COPYRIGHT: (C)2009,JPO&INPIT