A surgical treatment device which is used together with an endoscope, includes a sheath, a treatment portion, an operation portion including a grip portion, a scope holder, and a switching portion arranged between the grip portion and the scope holder. The treatment portion is arranged at the distal end portion of the sheath and includes first to third electrodes configured to treat a living tissue by using electrical energy. The operation portion is arranged at the proximal end portion of the sheath and configured to operate the treatment portion in a state that the grip portion is gripped. The scope holder is arranged at a proximal end portion of the operation portion and holds the endoscope in a state that the endoscope is aligned with the treatment portion. The switching portion is configured to switch between a first mode in which a treatment is given by using the first electrode and at least one of the second and third electrodes in the treatment portion and a second mode in which a treatment is given by using the second and third electrodes.
