PURPOSE: A diffuser clogging preventing apparatus is provided to easily remove foreign materials clogging a conduit line inside an air diffuser for preventing the blockage of the conduit line. CONSTITUTION: A diffuser clogging preventing apparatus comprises the following: a washing member(10) movably located on a conduit line in a tube shaped air diffuser(6) for removing foreign materials from the conduit line; and a transporting unit moving the washing member. The air diffuser is located inside a water treatment tank, and includes at least one hole. The transporting unit includes a screw rod(30) screw combined with the washing member, and a driver rotating the screw rod.
