Boiler is a hazardous equipment to have potential explosion ail the time. And not only it has malfunction at explosion. it lead to people death but also secondary accident such as explosion and fire. Therefore, this equipment should not be broken for keeping its own function. And also, high level of safety should be kept in the process of the use not to be malfunctioned. A large scale of accident due to boiler explosion can be preventive in advance. Boiler fracture is occurred by instant expansion (approximately 1700 time) from quick evaporation of rater in boiler, due to pressure decrease in boiler Emitting energy from it is tremendous and it is so dangerous because of its high temperature. Secondary explosion such as fire is also a main hazard occurring at fuel supply place. If any devices with high pressure is broken, then not only boiler vessel but also components of it are spread with high speed, causing secondary accident. This study is to analyze integrally accident cause of fire and flue tube boiler to have occurred pressure fracture actually, to show countermeasures to prevent accident loss from the fire and flue tube boiler.