To simply position plural drilling places, for radial knock of a vertical type large-size rotating machine, and facilitate working according as design required.

In the outer side of a ring base 28, a pair of temperature beams 29 are arranged in a radius direction, and also front and rear side fitting mounts 30 and 31 are fixed between both the beams 29 to previously provide drill mount fitting positions at an intervals design-commanded on the mounts 30 and 31, thereby drilledly providing plural fitting holes on these drill mount fitting positions respectively on neary the same radious to the center on the base 28. Then, drill mounts 34 are engagedly fixed to the drill mount fitting places in order to move a portable type drill 23, movably retained on the mount 34, in a radius direction, thereby performing drilling work by the gimlet 10 of the portable type drill 23.