A method of and apparatus for producing a hollow ring groove insert for an engine piston, which is inserted by casting near the top of a piston for an engine to constitute a ring groove and a cooling path adjacent to the ring groove. The hollow ring groove insert comprises a formed sheet ring and a ring body having an inner peripheral surface and a piston ring groove. A process for producing the formed sheet ring includes the steps of fitting a sheet ring on a forming die such that the sheet ring covers a forming groove; pressing a forming roll against the sheet ring while rotating the forming die with a floating ring being placed in a movable state where it is radially movable by disengagement from a tapered portion of a centering member, thereby forming circular collars on the sheet ring; pressing a cutting tool against the outer peripheral portions of the circular collars with the floating ring being placed in a state where it is centered and fixed in coincidence with the axial center of the forming die by engagement with the tapered portion of the centering member, thereby turning the outer peripheral portions of the circular collars; and pressing a deburring tool against the outer peripheral portions of the circular collars with the floating ring being placed in the same fixed state, thereby removing burrs from the circular collars.