PURPOSE: In drilling a center hole in the center of the end surface of a round bar of the like, to fit and secure a drill chuck at the low part of the round bar concentrically with the center of a receiving seat and to provide a pressing seat at the upper part thereof, thereby to make it possible to carry out drill processing of the center hole correctly and rapidly.

CONSTITUTION: A lower plate 1 is formed and two pieces of slide shafts 2 are fixed upwardly and perpendicularly to the centers at both sides of said lower plate 1. Then, guide cylinders 4 are provided at positions coincident with the interval of the shafts 2, and further upper plates 5 are inserted in the shafts 2 and made reciprocatable vertically, this unit being designated as a vertical slide mechanism A. Then, bearings 8 are inserted in the centers of the upper plates 5, and a receiving seat 12 formed with a conical hole 11 for receiving a material 9 is provided and inserted in the inner diameter part of each of bearings 8, said recriving seat being fitted thereto in a rotatable manner. A drill chuck 13 having a center drill 16 is fitted and fixed to the lower part of the receiving seat 12 concentrically with the center of said receiving seat 12, and pressing seat 15 is provided at the upper part thereof. Thus the drill processing of the center hole is carried out correctly and rapidly.