Building circulation system using curtain wall as ventilator

A ventilation system for a high-rise building is disclosed. The ventilation system comprises an external curtain wall 200 disposed to surround the building. The external curtain wall is spaced apart outwardly from the outer wall 22 by a certain distance. An external air suction port 210 is disposed in lower story portion of the external curtain wall 200. External air is introduced through the external air suction port 210. An air Stream exhaust port is provided in a space between the rooftop of the building and the upper end of the external curtain wall 200 extended horizontally to cover part of the rooftop of the building. The air stream exhaust port 220 has a pivot slit capable of being closed and opened. The external curtain wall 200 does not surround the entire four sides of the building, but part of the building sides is open without installing the external curtain wall 200 such that external air is directly introduced into the internal space of the building through a window 11 provided in the respective stories of the building, thereby using the external curtain wall as an exhausting space.