| abstract |
To provide a surface treatment liquid capable of making a base material including polyorganosiloxane on at least a part of a surface thereof hydrophilic stably over a long period of time, and provide a surface treatment method using the surface treatment liquid. In a surface treatment liquid including (A) resin and a (B) solvent, as the (A) resin, resin having a functional group I that is a hydroxyl group and/or a cyano group is used, and a functional group II that is a hydrophilic group other than the functional group I, and a ratio of a structural unit having an anionic group to total structural units of the (A) resin is 5 mol % or less, or resin including a cationic group including an anion moiety and a cation moiety that can be bonded to the (A) resin is used. |