A vascular embolization device includes a coil with a primary shape and an stretch resistant wire provided inside the coil, in which the stretch resistant wire is a multilayer strand including at least one core layer and at least one outer layer including one or more resin compositions and a biochemical active material, and the core layer is composed of a material with a tensile break strength higher than that of the outer layer. The vascular embolization device has the function of administering a biochemical active material and also has good flexibility.
