An artificial blood vessel which has excellent long-term patency and can be used stably in a living body for a long time. The artificial blood vessel has improved durability under pulsation and can withstand puncturing. The artificial blood vessel is made of an elastomer containing a multiplicity of cells throughout the structure thereof and comprises a layer (A) containing closed cells having no communicability therebetween; and a layer (B) containing open cells having mutual communicability therebetween. The surface of the layer (B) which is contiguous to the inner surface of the layer (A) and the wall surfaces of the open cells are coated with a thin film of crosslinked protein of biological origin. The layer (A) may be incorporated with a knitted or woven fabric which is not degradable in a living body. The layer (B) may further contain a synthetic resin short fiber distributed throughout the layer.