PURPOSE: To perform efficiently removal of a gelled article adhering to the inside of a cylinder, by making a driving source start by making the edge of a shaft of a brush connect with the coupling.

CONSTITUTION: When a gelled article is stuck to the inside 1' of a cylinder 1 of an extruder, a screw 2 is pulled out from a transmission shaft 9 by releasing the screw from the shaft 9 in a revolving state by slackening a coupling 4 of the screw 2 and a brush 10 is fitted in the cylinder 1. Then the coupling 4 is tightened so that a revolution of the transmission shaft 9 is transmitted to a shaft 11 of the brush 10. Then when a driving source 5 is started the brush is revolved also. It becomes, therefor, that the inside 1' is ground and the gelled article which has been stuck to the inside is removed mechanically. The shaft 11 of the brush 10 is made dividable by providing a connecting part 12 and it can be performed also that only a necessary part is ground by adding a short brush.