PURPOSE: To concentrically align two annular articles having relatively low dimensional accuracy with good accuracy by providing a holding means, back up means and rod part and concentrically positioning the first annular article and the second annular article respectively by means of their outside shape parts and bore parts.

CONSTITUTION: This concentrical aligning device has the holding means 1 for tentatively placing the first and second annular articles varying in the outside dimensions, the back up means 2 for lifting both articles, the rod part 3 and a pressing means 4 for pressing both articles from above to below. The back up means 2 is provided on a supporting member 18 and four pawl-shaped outside shape-holding parts 5 are integrally formed at the front end thereon to hold and lift the annular articles to be concentrically aligned in this part. An air cylinder 10 is mounted on a concentrical axial line 15 of the supporting member 18 and the rod part 3 is integrally mounted above this air cylinder 10. The front end on the upper side of the rod part is integrally provided with the taper shape part 8. The concentrical positioning by contact with the bore parts of the annular articles is executed by this taper shape part 8.