An operating for a circuit breaker including a pivoting handle for controlling opening and closing of the circuit breaker and resetting of the latch after tripping. The handle bears a resetting roller which cooperates with a cam surface of the latch, which surface has a first cam section and a second cam section separated by a slope change point. The second section corresponds to the reset position and the slope of this section is chosen in such a way as to obtain a stable reset position of the handle.