A rotation table of the present invention includes a seal mechanism portion including a sealing material arranged between a casing and a face plate, a casing-side grooved portion for forming a casing-side seal mounting groove which is formed on an end of the casing and retains the sealing material, and a seal holding plate for holding the sealing material, wherein a portion having the casing-side grooved portion and the seal holding plate are configured to be separable.