PURPOSE: To variably connect each division of machine to one side or the other side waste air drawing apparatus according to kinds or properties of the waste air even in machine operation, in a heat treating machine as transporting the materials to be treated through a continuously provided region to a transporting direction of materials to be treated.

CONSTITUTION: A waste air collecting conduit 5 extending along the whole of areas 2 generating at least two kinds of waste air is equipped each of the waste air collecting conduit is provided with connecting parts 4 led to each of the prescribed areas 2, each one of waste air drawing assembly 8, 9 is equipped at the end parts 6, 7 of the longitudinal direction of the prescribed waste air collecting conduit 5, and movable boundaries 12, 13, 14, 15, 16, 17, 18, 19, 20, 21 and 22 are equipped at longitudinal direction of the prescribed waste air conduit 5 between the drawing area of the two waste air drawing assembly 8, 9.