To alarm by sound when a main breaker reaches a given position in a drawer type circuit breaker.

A pot-shaped spring 32 is mounted on a trapezoid recessed part 29 of a rail at a given position. When a roller 25 moved together with a main breaker reaches the recessed part 29 of the rail 19, the roller 25 becomes free from a bent part of the spring 24 and dislocated at high speed by the spring 24 to collide with a bottom 29c and generate a sound. When the roller 25 is moved from the recessed part 29 to a projected part 30, the spring 32 is bent and the roller 25 is slid along a slanted face 29b of the recessed part 29.