Abstract: There is provided a medical high frequency treatment device (200). A distal portion of the high frequency treatment device (200) includes a high frequency treatment device knife (100) having a pair of scissors (10) so as to incise a biological tissue. The pair of scissors (10) is configured to be capable of shearing the biological tissue by pivoting in a direction closer to each other. Each of the pair of scissors (10) has a blade surface (13). Each surface of the pair of scissors (10) includes a formation region of a non-conductive layer (insulating film (12)) and an electrode region (19) where the non-conductive layer is not formed on the surface of the blade surface (13). With regard to at least one of the pair of scissors (10), a width dimension of the electrode region (19) in a plate thickness direction of the scissors (10) varies depending on a position of the scissors (10) in a longitudinal direction.