A medical material uses a nickel-titanium alloy wherein a polyelectrolyte has a reduced thickness while a sufficient amount of an antithrombogenic compound for production of a therapeutic effect is supported. The medical material in which a porous surface is formed on a nickel-titanium alloy to allow infiltration of a polyelectrolyte into the pores, to thereby reduce the thickness of the polyelectrolyte exposed on the surface of the nickel-titanium alloy while allowing supporting of a sufficient amount of an antithrombogenic compound due to contribution of the polyelectrolyte infiltrate.