PURPOSE: To prevent drying of a brush part by letting off the brush part from the inside of the holes of cylindrical holders, passing the same through liquid passages in said holders, guiding a high-viscosity and high-concn. liquid to the peripheral part of the brush part and pulling the brush part pack into the holes.

CONSTITUTION: The holes 4 and the liquid passages 5 around the holes 4 are penetrated and formed to a pair of the cylindrical holders 1, 2 in the axial line direction thereof. The root part 3a of a bundled fiber body 3 is fixed into the hole 4 of one cylindrical holder 1 and the brush part 6 in the front part 3b is formed slidably in the axial line direction within the hole 4 of the other cylindrical holder 2. Namely, the brush part can be let off from the inside of the hole of the cylindrical holder and the high-viscosity and high-concn. liquid can be guided to the peripheral face of the brush part through the liquid passage in said holder. The brush part can be retracted into the hole of the holder in the state of not exposing the peripheral face of the brush part to the external air and, therefore, the drying and solidifying of the brush part are obviated.