PROBLEM TO BE SOLVED: To provide an antithrombogenic material that can reduce the amount of adsorption of vWF, a coagulation system protein, to the base material surface while letting it have an anticoagulant activity.SOLUTION: The present invention provides an antithrombogenic material including a nitrogen-containing polymer having an alkylsulfonic acid group, an organic sulfur compound having an anionic anticoagulant activity, and a base material, and in which, when the surface is measured by X-ray photoelectron spectroscopy (XPS), the abundance ratio (Nratio) of nitrogen atoms to the abundance amount of all atoms satisfies the following formula 1. 6.0≤Nratio≤10.0 --- Formula 1 [In the formula, Nratio represents the abundance ratio (number of atoms %) of nitrogen atoms to the abundance amount of all atoms on the surface of the antithrombogenic material.].SELECTED DRAWING: Figure 1COPYRIGHT: (C)2020,JPO&INPIT【課題】抗凝固活性を持たせつつ、凝固系タンパク質であるｖＷＦの基材表面への吸着量を低減できる抗血栓性材料を提供すること。【解決手段】本発明は、アルキルスルホン酸基を有する窒素含有ポリマーと、アニオン性の抗凝固活性を有する有機硫黄化合物と、基材と、を有し、表面をＸ線光電子分光法（ＸＰＳ）で測定した場合に、全原子の存在量に対する窒素原子の存在比率（Ｎｒａｔｉｏ）が、以下の式１を満たしている、抗血栓性材料を提供する。 ６．０ ≦ Ｎｒａｔｉｏ ≦ １０．０ ・・・式１［式中、Ｎｒａｔｉｏは、抗血栓性材料の表面における全原子の存在量に対する窒素原子の存在比率（原子数％）を表す。］【選択図】図１
