[Object of the Invention] An object of the present invention is to develop an air curtain device generating parallel air flow based on the knowledge in that parallel air flow generated at the outlet of a turbulent flow runup zone does not include vortex flows and has strong air current interruption performance.[Disclosure of the Invention] An air curtain device comprises a first ventilation box comprising a discharge elbow provided with guide vanes, a honeycomb, an industrial use ventilating fan, a suction elbow provided with guide vanes, and a pre-filter, wherein the aforesaid elements are sequentially accommodated in a rectangular box whose one side surface is open and an outlet port of the discharge elbow provided with guide vanes and the pre-filter are disposed on the open side surface of the rectangular box, and a second ventilation box of the same structure as the first ventilation box, wherein the first ventilation box is put on an entrance floor with the discharge elbow provided with guide vanes above, and the second ventilation box is put on the entrance floor with the discharge elbow provided with guide vanes below, so that the first ventilation box and the second ventilation box oppose each other at their open side surfaces in a mutually upside-down manner and the first ventilation box and the second ventilation box are distanced from each other by a breadth Xg of the entrance, and wherein an entrance ceiling is provided to a breadth equal to the distance between the ventilation boxes so as to connect a top of the first ventilation box with a top of the second ventilation box, thereby forming an air curtain device entrance, wherein relation between the breadth Xg of the entrance of the air curtain device and a breadth D of the outlet ports of the discharge elbows provided with guide vanes is set at Xg≤5D.