PROBLEM TO BE SOLVED: To provide a drain pipe cleanser enabling its bleaching agent component to act on the whole inside of a drain pipe over a long period of time, thus enabling the inside of the drain pipe to be fully cleansed. SOLUTION: The solid drain pipe cleanser comprises a halogen-based bleaching agent component, a foaming component, a surfactant and a water-insoluble solid adsorptive component. COPYRIGHT: (C)2006,JPO&NCIPI