In a connecting device of an electrical apparatus in which a first solid insulator and a second solid insulator each molded as a solid insulator on a periphery of a center conductor are connected to each other via a flexible insulator, a high voltage electrode having an outer diameter larger than those of the center conductors is disposed in the second solid insulator, and a ground electrode having an inner diameter smaller than that of an outer ground layer of the second solid insulator and larger than the outer diameter of the high voltage electrode is disposed in the first solid insulator. Electric field directions at an interface between the first solid insulator and the flexible insulator and at an interface between the second solid insulator and the flexible insulator are directions along the respective interfaces.