Electric circuit breaker device

An electric circuit breaker device comprising:

• a housing including an accommodating space inside, the accommodating space extending in one direction and including a projectile accommodating portion formed at one end side and an arc-extinguishing region portion formed at the other end side;
• an igniter provided at the housing;
• a projectile accommodated in the projectile accommodating portion and configured to be projected from the projectile accommodating portion toward the arc-extinguishing region portion side along the accommodating space by energy received from the igniter;
• and
• a conductor piece provided at the housing and forming a portion of an electric circuit, the conductor piece including, at a portion of the conductor piece, a cutoff portion to be cut off by the projectile, the cutoff portion being disposed crossing between the projectile accommodating portion and the arc-extinguishing region portion, wherein
• the projectile includes, on a tip end side, a cutoff surface configured to cut off the cutoff portion at a time of actuation of the igniter, and
• at least one magnet is disposed at the arc-extinguishing region portion of the accommodating space.