Abstract: Disclosed is an apparatus for measuring a dimension of a manufactured article to be worked on a cylindrical grinding machine. The apparatus includes non contact-type measuring sensors capable of measuring the outer diameter and cylindricity of the manufactured article while the manufactured article is mounted on the cylindrical grinding machine. The apparatus comprises a main body which is positioned above a cylindrical grinding machine. The main body includes a bed having a through opening formed through a center thereof and a plurality of support members for supporting the bed. A sensor attachment of the apparatus is positioned on the bed. A sensor attachment includes at least two pairs of non contact-type measuring sensors. The pairs of non contact-type measuring sensors are spaced opposite from each other in order to measure the outer diameter and cylindricity of the manufactured article.