The present invention provides a hydrophobic polymer compound capable of inhibiting the blood coagulation reactions in both the primary hemostasis stage involving platelets and the coagulation thrombus formation stage involving blood coagulation factors, which hydrophobic polymer compound can be firmly immobilized on the surface of a medical device or medical material in a state where the compound retains its anticoagulant activity. The present invention provides a hydrophobic polymer compound in which a polymer compound inhibiting platelet adhesion is bound with a compound inhibiting blood coagulation reaction.
