PURPOSE: To simply, effectively and rapidly calculate other unknown numeric value from partial known numeric value in a safe range for eliminating stone flying to decide numeric values of specifications necessary to execute a perforation explosion construction.

CONSTITUTION: In a perforation explosion construction having as specifications a perforation length H, a minimum resistance wire length W, a charge length N, a perforation interval length (fracture radius) D, a perforation diameter (d), a fracture baserock volume V, a charge amount L and a blasting coefficient (c), other unknown numeric value is judged to be calculated from partial known numeric values by utilizing relationship among the specifications under conditions that a distance between a vertex of the length N and a ground surface is set to the length W, the length W is set equal to at least the length (fracture radius) D, but not set to smaller value.