To provide a method for maintaining a twin screw type carrying device capable of restoring wear of an inner surface of a casing and a tip of each rotor after operation for a long time, simply, quickly and at a low cost.

This invention relates to the method for maintaining the twin screw type carrying device TS provided with a male rotor 1 of a male screw shape, a female rotor 2 of a female screw shape arranged with meshing with the male rotor 1, and a gourd shaped section type casing 3 surrounding the rotors 1, 2 with a designated gap, and compressing and sending slurry material in the casing 3 in an axial direction by alternately rotating the rotors 1, 2 in reverse direction. When the inner surface of the casing 3 and tips of the rotors 1, 2 wear after operation for a long time and gaps thereof increase, spacer plates 25, 26 for returning the gap to a designated value are attached on the tip of the rotors 1, 2.