Abstract: A water leak disclosing agent and a water leak detection method are disclosed. The water leak disclosing agent is a pigment-containing colored tablet or a pigment solution, wherein the pigment material stains the water if it is put thereinto so it is adopted as the disclosing agent for water leak detection. In accordance with the water leak detection method, the colored tablet is plunged into a water pipe or a floorslab of a floor or a bathroom is filled with the pigment solution. As a result, the leaky position can be identified easily and correctly according to the color of the oozed colored liquid.