PURPOSE: To easily form a projected vein ring for an annular seal on the external circumferential part of the opening of a face part by pressurizing and revolving a revolving member locked from the other end of a columnar working tool part set in an inclined state at an eccentric position through a pressure revolving mechanism.

CONSTITUTION: First, the lower end of this device abuts in vertical contact with a surface 1e to be worked on the upper surface of a cylinder block 1. In this time, the height of the lower end of this device is adjusted so that it projects a little below the lower end of an adjusting external cylinder 19 and is positioned above the lower ends of the annular edges 18a, 18b, 18c of the columnar working tool 18 and, consequently, the annular edges of the columnar working tool part adjusts the height of the projected pulsating rings 2, 3 to be formed on the cylinder block 1 to a prescribed height. When a motor starts as a grip part 11 is pressed, the columnar working tool part 18 revolves in an inclined state, one place on the circumferential edge of the annular edges shifts its abutting place successively, revolves and moves as it draws a circular locus on a surface 1e to be worked. In this way, annular projected vein rings 2, 3 are formed on the surface 1e to be worked.