DEAERATOR

PROBLEM TO BE SOLVED: To provide a deaerator for a high speed chromatography, having deaeration performance of high replacement efficiency with small volume. SOLUTION: A deaeration module is constituted of a flat bag-like member in which the peripheral edge of two deaeration membrane sheets 101a, 101b in about strip-like form are sealed to form an inner space and which has an eluent introducing port 104 and an eluent discharging port 105 for introducing and discharging the eluent to and from the inner space respectively which are independently fitted at the positions separated from each other to the inner space, perforated plates 102a, 102b installed in close contact with the front and rear surfaces of the bag-like member respectively and having about the same shape as that of a deaeration membrane sheet for suppressing the expansion of the inner space of the bag-like member, and a pair of holding frames 106, 107 for fixing the overlapped peripheral edges of the bag-like member and the perforated plates 102a, 102b to hold them at the front and rear of the perforated plates so that the front and rear areas surrounded by the peripheral edges are exposed, and the module is housed in a vacuum chamber, which is evacuated by a vacuum pump.