An antithrombotic material has an excellent anticoagulant activity and can form a stable coating layer on a base material through a simple and mild coating process. An antithrombotic material includes a copolymer configured to have 75% by mole to 25% by mole of a repeating unit (A) derived from diacetone(meth)acrylamide represented by the following formula (1) (wherein R1 is a hydrogen atom or a methyl group) and 25% by mole to 75% by mole of a repeating unit (B) derived from a monomer having at least one sulfonate group selected from a group consisting of 2-(meth)acrylamide-2-methyl-propane sulfonic acid, vinyl sulfate, allyl sulfate, styrenesulfonic acid, sulfoethyl(meth)acrylate, and sulfopropyl(meth)acrylate in a molecule, or a salt of the monomer (the total amount of the repeating unit (A) and the repeating unit (B) is 100% by mole).
