To rescue victims and to protect rescue workers from a secondary disaster by attaining a self-defence tool by tightening and fixing the lower end parts of left and right plates opened in an acute triangle by fixing metal fittings at the time of emergency, adding and connecting many of them when it is required and quickly forming a hurriedly constructed tunnel for withstanding the impact and heavy pressure of a falling object.

When the rescue worker 1 present near a disaster spot pulls out the safety pin of this self-defence tool 4 and detaches a closing metal fitting 8, the left plate 5 and the right plate 5' are opened in the acute triangle by an elastic body 7 and the fixing metal fittings 8 disposed on both sides at a lower part in front and at the back of the self-defence tool 4 become horizontal one line. Then, the tightening part 10 of the fixing metal fitting 8 is tightened by the fixing screw 11 of the left plate 5 and the self-defence tool 4 is rigidly tightened to the rigid acute triangle. Then, advancing is performed by putting on the self-defence tool 4 and it is installed at the target front line of the disaster. Then, land slid earth and sand and fallen rocks are raked up and sent backwards. When a clearance is made in front, the self-defence tools 4 are added one after another and connected by plural connection bodies 17 and the strong triangular hurriedly constructed tunnel is completed to a safe place.