The electronic endoscope (2) transmits the image pickup signal obtained by the image pickup unit (14) to the processor (3) as a differential signal obtained by converting the image pickup signal into digital serial data, and the differential signal is sent to the processor ) Of the transmission path including the cable (17) so that the quality of the output waveform to the processor (3) becomes constant, which is arranged at the output stage of the transmission section (15) And a filter section (16) whose constants are adjusted according to the loss.電子内視鏡(2)は、撮像部(14)で得られた撮像信号をデジタルシリアルデータに変換した差動信号としてプロセッサ(3)に送信するものであって、差動信号をプロセッサ(3)に送信するための送信部(15)と、送信部(15)の出力段に配置され、プロセッサ(3)への出力波形品質が一定になるように、ケーブル(17)を含む伝送路の損失に応じて定数が調整されたフィルタ部(16)と、を有する。
