To provide a method preventing the clogging of a filter, by which filtratin performance is rapidly recovered by easily and surely removing a solid material causing the clogging from a filtering/material when the filtering/ material is clogged.

The solid component in an original liquid 1, which is stuck to the outside surface of a filtration wall 20 of a filtration cylinder 4, is removed by making a filtrate 11 to back flow through the filtration cylinder 4, which has the filtration wall 20 formed by arranging stripes 19 dense in parallel and is for filtering the original liquid 1 by passing the liquid 1 through from the inside to the outside of the filtration wall 20, to cause the multiplication of the jetting force when the filtrate 11 is jetted from the inside to the outside of the filtration wall and the centrifugal force generated by the rotation of the filtration cylinder 4.