To provide a waterproof structural body, its waterproof performance inspection method, and a waterproofing construction method capable of easily detecting the presence/absence of damage to a waterproofed face.

A sheet type cushioning material 3A forming a furring layer 3 is arranged on a concrete slab 1A, and a waterproof sheet 5A forming a watertight layer 5 having an electrical insulation characteristic is arranged on the sheet type cushioning material via a metal film 4A forming an electrically conductive layer 4. In the waterproof structural body constructed in this way, an earth part is formed in a part of the watertight layer 5 or the conductive layer 4, and the presence/absence of excitation to the conductive layer 4 is detected by sequentially bringing a measurement electrode 18 impressed with a predetermined voltage into contact with respective parts on the surface of the watertight layer 5. If there is a damaged part such as a pin hole in the watertight layer 5, an electric current flows through the conductive layer 4, so that the damaged part in the watertight layer 5 can be surely detected, and when the damage is repaired, water leakage can be prevented.