A blood vessel dissecting device is disclosed, which includes a dissecting device which, when being inserted into a living body along a blood vessel, dissects tissue in a direction of alignment thereof with the blood vessel, and a cutting device which, when being inserted into the living body along the blood vessel, cuts tissue surrounding the blood vessel in a direction of alignment thereof with the blood vessel. The cutting device includes a main body section which is inserted into the living body and holds the tissue between itself and the dissecting device, and a cutting section which cuts the tissue held between the main body section and the dissecting device.
