A connection structure for superconducting cables includes: superconducting cables that are connected to each other and include cable cores containing formers and superconducting conductor layers, and each cable core is housed in a thermal insulation tube with a cooling medium, wherein the cable cores include electric insulating layers obtained by winding insulating sheets around the superconducting conductor layers, the electric insulating layers on both sides of a conductor connecting part, in which the formers and the superconducting conductor layers are connected to each other, include taper shape portions each having a diameter reducing towards the conductor connecting part, each taper shape portion is formed so as to have an inclination angle changing in a stepwise fashion by a plurality of tapered portions among which a tapered portion nearer the conductor connecting part has smaller inclination angle, and a reinforcing insulating layer is provided between the taper shape portions.