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. 電子内視鏡装置は、挿入部、操作部、及び外部機器に接続されるよう操作部から延出するユニバーサルコードを備える電子内視鏡と、挿入部の先端とユニバーサルコードに設けられた接続コネクタとの間に選択的に配置される、長さが同一で直径が異なり、直径に対応した表面積の総合シールドを備えた複数種類の信号ケーブルと、予め定めた表面積で構成され、直径が小径な信号ケーブルの外装に被覆してシールド補強部を形成し、シールド補強部を小径な信号ケーブルの総合シールドに電気的に接続することによって、シールド補強部の表面積と小径な信号ケーブルの総合シールドの表面積との和を、直径が大径な信号ケーブルが備える総合シールドの表面積に対して、同一、または、それ以上に設定する電磁的被覆部材と、を具備する。