An elongated electrosurgical instrument (1) comprises a first means (3) for at least cutting tissue of a patient during surgery by application of electrical energy supplied from an electrosurgical generator to a surgical site in response to operating a switch means (5). The instrument has an elongated main body (2) having a first end (7) with a first opening (15) through which the first means (3) protrudes. The first means (3) has a securing part (36) for securing to a holder (33) associated with the first end (7) of the elongated main body (2) of the electrosurgical instrument (1). The securing part (36) of the first means (3) has a first engagement part (37) of a first pentagonal cross-section, and the holder (33) includes a complementarily second engagement part (38) for receiving at least a part of the first engagement part (37).電気手術用器具(1)は、スイッチ手段(5)の操作に応じて電気手術用発電機から手術部位に供給される電力により、手術中に、少なくとも患者の組織を切断するための第1手段(3)を備える。前記器具は、前記第1手段(3)が突出する第1開口(15)を形成された第1端(7)を有する長尺本体(2)を備える。前記第1手段(3)は、電気手術用器具(1)の長尺本体(2)の第1端(7)に係合するホルダ(33)に固定するための固定部(36)を有する。前記第1手段(3)の固定部(36)は第1五角形断面の第1係合部(37)を有し、前記ホルダ(33)は第1係合部(37)の少なくとも一部を相補的に保持するための第2係合部(38)を有する。
