To more enhance safety in an ignition prevention structure in an installation handling combustible fluid having a high risk of ignition under a high-temperature environment.

In this ignition prevention structure in the installation handling the combustible fluid, the outer surface of a high-temperature object 1 is covered with heat insulation material 2, and also the outer surface of the heat insulation material 2 is covered with a metal mesh 3. Further, the outer side of the metal mesh 3 is covered with an exterior member 4, and a purge gas supply pipe 12 for supplying purge gas is formed in a space inside of the exterior member 4.