A descender is for work at height, climbing, mountaineering, speleology or other practices using a rope. The descender device for a textile rope (F) includes a casing in which a cam mechanism (10) and an actuating lever (3) for the cam mechanism (10) are housed. The casing (2) includes a return element (13) for the rope (F). The cam mechanism (10) includes a lever pin (29) rotatably actuated by the actuation lever (3) and a movable cam (25) which is rotatably movable between a deactivation position and a locked position in which the movable cam (25) presses on the rope (F) against the return element (13). The lever pin (29) acts on a rocker member (32) which is integral with the movable cam (25) during a first rotation step of the lever pin (29) in a direction opposite to the activation direction of the movable cam (25).