The invention relates to the field of drilling and blasting operations, and more particularly to confining gaseous explosion products in a charge cavity, and can be used in rock blasting using borehole charges. The technical result of the invention is that of reducing the specific charge of explosive per cubic metre of blasted rock mass, increasing the fragmentation of the rock mass, making it possible for explosive to be loaded into and work effectively in a borehole with excess water pressure (flooded boreholes), providing ease of use and structural simplicity, providing ease of transportation and storage since the device can be dismantled to compact dimensions, and reducing the weight of the structure. A further technical result is the possibility of using devices of a single type in boreholes of different lengths and types (flooded or non-flooded), thus making it possible for the claimed device to be used as a universal device for all types of boreholes. The above-mentioned technical result is achieved in that the claimed borehole plugging device, which is made of a pliable polymer material and has elements with a shape, the outside diameter of which is commensurate with the diameter of a borehole, and an axial internal cavity, is characterized in that it consists of a rod with a cruciform cross section, having identical dome-shaped, slotted elements fixably mounted thereon from each end.