A resectoscope device comprises a sheath body having an elongated hollow sheath to be inserted into a urethra. A handle part has a slider connected to the sheath body and slides in the axial direction. An observing scope is inserted into the sheath through the handle part and sheath body. An electrode is inserted through the sheath, and is removably connected at the rear end to the slider. The electrode has a resecting part that can be projected out of and retreated into a beak opening at the tip of the sheath by the sliding operation in the axial direction of the slider. A stabilizer is provided in the electrode and the scope is able to be inserted therethrough so that a forked part of the electrode may be housed in contact with the inner peripheral surface of the beak and the resecting part may be housed without catching on the beak opening. A spacer which holds the stabilizer constant with respect to the inside surface of the sheath, is provided to set the scope, electrode means and handle without inclining them with respect to the inside surface of the sheath.