PURPOSE: To provide a drilling apparatus having universal utility capable of coping with even a change in the size of shape steel to be drilled.

CONSTITUTION: A drilling apparatus is provided with a machine frame 1 having a pair of guide shafts 11 and a drilling machine body 2 guided by both guide shafts 11 to move forward and backward. Both guide shafts 11 are provided on the tip parts respectively with shape steel holding parts 3. The shape steel holding part 3 is provided with an upper horizontal wall part 42 fixed to the tip parts of both the guide shafts 11, a lower horizontal wall part 43 parallel thereto and a connecting wall part 41 for interconnecting these wall parts. The lower horizontal part 3 is provided with a threaded hole 48 parallel to the extension line of a drill 25. A male screw member 50 for pressing a shape steel cross part to be drilled against the upper horizontal wall part 42 is screwed into the threaded hole 48. The upper horizontal wall part 42 is provided with projecting parts 46, 47 for receiving a press force of a male screw member 50 to be located in the respective apexes of a triangle surrounding the male screw member 50.