The present invention aims to provide an antithrombogenic material which has a reduced thickness of its coating material, and which maintains high antithrombogenicity for a long period. The present invention provides an antithrombogenic material comprising: a coating material containing: a cationic polymer containing, as a constituent monomer, a compound selected from the group consisting of alkyleneimines, vinylamines, allylamines, lysine, protamine, and diallyldimethylammonium chloride； and an anionic compound containing a sulfur atom and having anticoagulant activity； and a base material whose surface is coated with the coating material； wherein the cationic polymer is covalently bound to the base material； the anionic compound containing a sulfur atom and having anticoagulant activity is immobilized on the surface of the base material by ionic bonding to the cationic polymer； and the average thickness of the coating material is 15 to 400 nm.
