An electrosurgical instrument, in particular for argon plasma coagulation, includes a handpiece 10, an electrode (11) connected to the handpiece (10), a shaft (12) which surrounds the electrode (11) and is held in the handpiece (10), and an operating mechanism (13), which comprises at least one rotary knob (14) arranged on the handpiece (10). The shaft (12) is axially movable relative to the electrode (11) and a shear force can be applied to it by operating the rotary knob (14). The handpiece (10) has a brake device which exerts a braking force on the shaft (12), and the operating mechanism (13) forms a transmission gear (15) which is connected to the shaft (12) for transferring the shear force.