To eliminate such a problem that smoke exhausted from a stack is pushed back by exhausted gas from a cooling tower in dependence upon direction of wind, so as to cause air-pollution by smoke.

A stack and cooling tower assembly is composed of a hexagonal stack outer cylinder 21, a plurality of cooling tower bodies 11 arranged making contact with the wall surface of the stack outer cylinder 21 so as to commonly use the wall surface of the stack outer cylinder 21. With this arrangement, smoke vortices induced in smoke exhausted form the chimney outer cylinder 21 are elevated by exhaust gas vortices induced in exhaust gas exhausted from the cooling tower bodies 11 even though a wind blows in any direction, and the exhaust gas and the smoke are merged together so as to affect an upward force. Accordingly, occurrence of depression by exhaust gas vortices is prevented while an included heat value is increased due to mergence between the smoke and the exhaust gas in order to a climbing height of the smoke in order to restrain the concentration of the smoke from increasing. It is noted that the upward force can be exhibited with a highest degree of efficiency since the distance between the stack outer cylinder 21 and the cooling tower bodies 11 becomes minimum.