Provided is a dehumidifier including an adsorption column allowing a to-be-treated gas produced by electrolysis of water to circulate therethrough so as to allow moisture in the to-be-treated gas to be adsorbed therein, wherein the adsorption column includes an adsorbent capable of adsorbing moisture, a column body having a housing region containing the adsorbent, and a heating unit arranged within the column body and capable of heating the adsorbent so as to cause desorption of the adsorbed moisture from the adsorbent, and the column body is a tube having a bent portion.