Abstract: An hydraulic plunger for cleaning a clogged drain composed of a casing with a piston movable therein and being open at one end. A fitting is provided on the open end that fits against the drain inlet. A water inlet is provided in the casing to permit water to fill the casing on the side of the piston that is open to the drain pipe and the drain pipe to the stoppage therein. An electromagnetic unit is carried within the casing and has a driven member that strikes the piston to create a relatively large impact force against the water and stoppage in the drain.