To improve an insertion operability of an explosive increment into a protective cylinder, a connecting operability, a sympathetic detonation and a manufacturing cost by forming an increment holder in an elliptical cylinder having a shorter short diameter than a diameter of the explosive of the increment, and forming a protective cylinder connector in a cylindrical state.

An explosive increment 1 is inserted into an explosive protective cylinder. Here, a reference numeral 4 denotes a short diameter of an ellipse. and a numeral 5 denotes a long diameter of the ellipse. The protective cylinder is connected by elliptically deforming an end of a contained increment holder 3 of an explosive increment 1 via a protective cylinder connector 2 of other explosive protective cylinder to be connected by a finger tip, and inserting it. Thus, even without using a connecting joint, a foreign matter is not inserted between the increments 1, and a detonation is not interrupted. And, since the joint is not used, its operation is not complexed. Further, since its structure is simple, it can be manufactured inexpensively. Since the cylinder is transparent, a connecting state can be visually confirmed even in a tunnel excavating work. In addition, since the shape of the holder 3 is formed in the elliptical state, a generating frequency of a misfiring residual explosive is lowered.