Provided is a medical base material which is suitable for the regeneration of the circulatory system including aorta that is exposed to a high pressure from a lumen and which can be bioabsorbed after implantation. The medical base material according to the present invention has a sheet-like form a tubular form or a combination of these forms can be implanted into a living body for the regeneration of the circulatory system and has a multi-layer structure having at least an inner layer that is arranged on the intima side of the circulatory system and an outer layer that is arranged on the adventitia side of the circulatory system relative to the inner layer and is made from a material containing at least stereocomplex-type poly(lactic acid) wherein the layer arranged on the adventitia side of the circulatory system relative to the inner layer is formed in a porous form so that a feeding blood vessel can reach the inner layer or can pierce into the vicinity of the inner layer.
