To provide an electrochemical battery, furnishing a safety valve of high reliability and an electric circuit breaker.

When the inside of a can reaches to a prescribed gas pressure level, a fragile part 48 of a stripper contact disk 28 is torn off from the stripper contact disk 28 at a welded part W, and an electric circuit breaker operates. When an inner pressure generated by the generation of gas is made extensively higher than the level for the operation of the circuit breaker, a fragile part 70 of a vent valve contact disk 30 is broken, and a high pressure gas escapes from the air vent 54 of a reverse U-shape end cap 20.