PURPOSE: To easily return an oil well to the former condition after extinguishing fire even if the fire extinguishing time is shortened by preventing re-fire of an oil well after the completion of fire extinguishing at the time of a fire of an oil well and eliminating the need of large quantity of water at the time of extinguishing a fire so as to eliminate the danger of a fire extinguishing work.

CONSTITUTION: A cutting device 2, a cap device 3 and a transport car 4 are loaded on a carrier car 1. The cutting device is capable of moving in the carrier car, and a cutter 7 is provided on the forward end portion. The cap device is locked and transported by a transport car movably disposed on the cap device, and includes a valve element 19 and a storing portion 12 storing a thermosetting resin 11 in a covering body 10 made of low-melting point metal, wherein the valve element is held by a heat deterioration rope 29.