Abstract: A circuit breaker includes a shell, a movable press strip, a metal strip, a C-shaped plate spring, and three conductors. A first and a second conductor are inserted through the bottom of the shell, respectively have an upper end extending up in the shell, with a first contact point on its upper end of the first conductor, with an upper end of the second conductor connected with a metal strip, which has one end facing under a first press member of the press strip and an elastic contact strip with one end provided with a second contact point facing under the first contact point. A C-shaped plate spring has two lower ends connected with the metal strip, and a curved-up portion facing a second press member. The contact strip may disfigure by high heat caused by excessive current, curling upward to force the first contact point snap off the second contact point to cut off the circuit breaker.