To instantly open a head as soon as starting by constituting a heat sensing part breaking mechanism so as to give external force to a heat sensing part by fluid pressure to break.

At the time of opening a manual starting valve 9 at the time of a fire, a foaming solution passes through a feeding pipe 8 and flows into a cylinder container 2 through the feeding port 7 of a forcedly opening device 1. A piston part 3 moves upward against the spring force of a spring 3a by the solution pressure. Thereby, a stopper 5 is pulled out from the stopper insertion hole 4a of a breaking pin 4. Then, the moving regulation of the pin 4 is released and the pin 4 moves in the direction of an arrow A1 by the spring force of the spring 6. At this time, the hook part and the projecting part of the pin 4 break a glass valve 11 to open a heat 10 to discharge the foaming solution. Then, the heat is instantly opened as soon as starting.