To facilitate the recognition of a contact part of a thread with a guide by visual observation by developing the brown color at a guide way of the guide by forming the guide for slidably guiding the fiber by using a sintered body containing a specific amount of zirconia containing Dy3O3 and CeO2 based on barium titanate.

This barium titanate-based sintered body having brown-colored barium titanate-based sintered body without reducing the material strength by suppressing the increase of voids is obtained by adding 0.5-15 wt.% zirconia containing Dy3O3 and CeO2 to 100 wt.% barium titanate. The sintered body preferably contains impurities regulated so as to be about 3 wt.% or less of Al2O3, about 0.1 wt.%; or less of SiO2 and about 5 wt.% or less of other impurities. A roller guide 1 of a fiber machine 2, having a guide face is formed by using the barium titanate-based sintered body having a proper hardness, conformable to a thread or the like and hardly providing damage to the other. As the result, a worn state of a thread-piecing part 3 of the guide face can be easily recognized by visual observation.