[Problem] To provide a surface control agent for a water-based coating, the surface control agent having both cissing prevention properties and overcoatability when used for applications requiring excellent appearance and overcoatability.
[Solution] The surface control agent for a water-based coating includes: a copolymer containing, as constituent monomers, a dibasic acid ester (A) having a polymerizable unsaturated double bond in an amount of 10% by mass or more and 99% by mass or less, and an ether group-containing polymerizable unsaturated monomer (B) having a (meth)acryloyl group, a vinyl ether group, or an allyl group in an amount of 1% by mass or more and 90% by mass or less, wherein the copolymer has a weight-average molecular weight of 1,000 or more and 100,000 or less.