[Problem] To improve liquid dispersibility in a filler and improve the efficiency of processing a gas by providing a perforated plate on the filler and supplying a liquid onto the filler through openings in the perforated plate; moreover, to prevent a reduction in contact efficiency due to marine organisms infiltrating the device. [Solution] A prescribed filler (20) having substantially uniform flow channels in relation to a cross-section is provided inside a standing column (1), a gas to be treated is blown into the column from below the column, a perforated plate (5) having openings disposed in a substantially uniform manner is provided above the prescribed filler (20), a seawater distribution and supply means (3, 4) for distributively supplying seawater to an upper surface of the perforated plate is provided above the perforated plate (5), and contact is brought about between the gas blown up into the column and the descending liquid, so that the gas is treated.