To provide a gas dissolution device for liquid with a simple structure which can dissolve gas in liquid effectively.

A gas dissolution device for liquid comprises: a first duct in which a bottom edge along a vertical direction is closed; a communication duct communicating a first upper position and a first lower position which are different positions in the vertical direction of the first duct; liquid supply means supplying liquid to a supply position present in the communication duct; liquid extract means extracting liquid from an extract position present in the communication duct; and blowing means forming circulation flow where liquid circulates through a circulation duct including the first duct and the communication duct by buoyancy of air bubble which gas forms in the first duct liquid by blowing the gas on a blowing position at a position in the first duct more downward than the first upper position. The circulation flow leaves the blowing position, passes the extract position, passes the supply position and comes back to the blowing position.