in vivoThe purpose of the present invention is to provide an instrument for capturing free thrombi which can inhibit a blood coagulation reaction at a primary hemostasis stage in which platelet is involved or a coagulated thrombi formation stage in which a blood coagulation factor is involved whereby it becomes possible to secure the capture of free thrombi and to prolong the usable time of the instrument. The present invention provides: an instrument for capturing free thrombi in which a compound having an anti thrombin capability is immobilized on the surface thereof and a method for capturing free thrombi which comprises capturing free thrombi in blood using the instrument for capturing free thrombi.
