The endoscope system 1 includes a flexible endoscope 10 having a flexible insertion portion 11, an operation portion 12, and a flexible channel 14 inserted through the insertion portion 11, a flexible endoscope 10 inserted through the channel 14 A treatment instrument 20 whose treatment section 22 protrudes from an opening 14 B at the distal end section, a counter electrode plate 40, and a power supply 30 for outputting high-frequency power, and the endoscope 10 is controlled by high-frequency power input from the power supply 30 A power receiving portion 19 including a power transmitting electrode 18 for generating an AC electric field to be applied to the channel and the power received by the power receiving portion 29 including the power receiving electrode 28 with the treatment instrument 20 capacitively coupled with the power transmitting electrode 18 is outputted to the treatment portion 22 .内視鏡システム1は、可撓性の挿入部11と、操作部12と、挿入部11を挿通する可撓性のチャンネル14と、を有する軟性内視鏡10と、チャンネル14を挿通して先端部の開口14Bから処置部22が突出する処置具20と、対極板40と、高周波電力を出力する電源30と、を具備し、内視鏡10が、電源30から入力される高周波電力によりチャンネルに印加する交流電界を発生する送電電極18を含む送電部19を有し、処置具20が送電電極18と容量結合する受電電極28を含む受電部29が受電した電力が処置部22に出力される。
