A gas scrubber is provided to prevent reduction of an exchanging period of an absorbent by preventing absorption of dust on a particular part. A canister(110) includes an absorbent(141) supported by a protective net(143). Flanges(113) are installed at upper and lower parts of the canister. An upper cap(120) includes an exhaust tube(127) for exhausting the gas cleaned by the absorbent, and a flange part(121) connected to the flange. A lower cap(130) includes an inflow tube(137) for receiving harmful gases, and a flange part(131) connected to the flange. A groove is formed in a circumferential direction of the flange part. An O-ring is formed at the inside and/or the outside of the groove. A protrusion is formed at the flange to be inserted into the groove. The O-ring is loaded on a loading groove which is formed at the inside and/or the outside of the protrusion.
