To provide an ultrasonic sludge pulverization fuel oil filter which has such a function that sludge particles stuck to filter net are pulverized by ultrasonic acceleration, fuel components such as wax and asphaltene are dissolved into fuel oil during passage and a stuck residual solid component is effectively discharged to the outside by mounting an ultrasonic transmitter to a conventional duplex fuel oil backwashing filter.

A vibrator 1 and conical upper and lower reflective plates 2, 3 which apply ultrasonic wave to the inside of the filter net are attached to one hollow shaft 4 on the center of the conventional fuel filter. Further, such a function that the sludge stuck to the filter net is pulverized by actuating the vibrator with a filter difference pressure transmitter 6 and, thereby, the residual solid content is drained by backwashing is provided.