PURPOSE: To facilitate automatic assembly by hooking a cradle on a trip link with the spring force of a reverse spring while the reverse spring is fitted between the first spring reception section of a moving contact and the second spring reception section of the cradle.

CONSTITUTION: A handle 1, a moving contact 2, a fixed contact 3, a reverse spring 4, a trip link 5, a cradle 6, and an electromagnet 33 are provided, a connecting shaft 14 operating the handle 1 is moved, the action line connecting the connecting shaft 14 and the first spring reception section 16 crosses the second spring reception section 28, thus the reverse spring 4 is reversed, thereby the moving contact 2 is opened or closed. A hooking section 20 is released from the trip link 5 when an abnormal current flows, the cradle 6 is rotated around the second fixed shaft 27 by the reverse spring 4, an forced opening section opens the moving contact 2, and the reverse spring 4 is reversed. A member with high degree of freedom such as a compression spring can be used for the reverse spring 4, thus automatic assembly is facilitated.