PROBLEM TO BE SOLVED: To provide a defoaming material with a half duplex structure wherein such problems as dislocation of an inner layer when a conduit is inserted or clogging of an opening of the conduit with the inner layer hardly occur while having excellent defoaming properties.SOLUTION: The defoaming material 20 includes an outer layer 21 and the inner layer 22 disposed on the inner side of the outer layer 21, and has the half duplex structure with the inner layer 22 disposed on the upper side only. The upper end of the outer layer 21 is continued to the upper end of the inner layer 22 via thin-wall parts 101a and 101b.
