An electronic endoscope apparatus includes an electronic endoscope including an insertion portion, an operation portion, and a universal cord which extends from the operation portion so as to be connected to an external device； a plurality of types of signal cables which are selectively placed between a distal end of the insertion portion and a connection connector that is provided at the universal cord, have equal lengths and different diameters, and include overall shields having surface areas corresponding to the diameters； and an electromagnetic covering member which is configured to have a predetermined surface area and covers, as a sheath, a signal cable having a small diameter to form a shield reinforcing portion, the shield reinforcing portion electrically connected to the overall shield of the small-diameter signal cable causing a sum of the surface area of the shield reinforcing portion and the surface area of the overall shield of the small-diameter signal cable to be set to be equal to or larger than the surface area of the overall shield of a signal cable having a large diameter.
