To provide a box-body airtight structure, in which the scattering of a part by an explosion is inhibited minimally by a simple structure and man-hours for a design are decreased, which is lightened, the space of which is diminished and the cost of which is reduced.

In the box-body airtight structure, electronic equipment is housed to the hermetically sealed inside composed of a plurality of the box bodies. In the airtight structure, a plurality of the box bodies are aligned mutually, the first box body 10 and second box body 20 of the aligned box bodies are clamped to the second box body 20 via the first box body 10 by a bolt 30 with a head section 30a and fast stuck mutually. The clamping section 22a of the second box body 20 is formed of the quality of the material having a strength weaker than the quality of the material of the bolt 30 so that the clamping section 22a of the second box body 20 clamped by the bolt 30 is broken and a stuck state is released, when the internal pressures of the box bodies rise. The slip-off of the second box body 20 is prevented, by clamping a nut 40 on the end-section side of the bolt 30.