To provide a drilling machine which can position an edge accurately while coinciding with the pitch and drill a desired hole to a work, at the drilling time of plural holes to the work such as a pipe with a prescribed pitch.

This is a drilling machine, provided with a work clamp 1 having a guide hole for drilling a hole in a work 3, a prop 4 erected on the work clamp 1 and a drilling machine 20 installed on the prop 4 slidably through a slide member, which can drill the work held in the work clamp by an edge 21 provided on the drilling machine 20, while moving the drilling machine 20 fixed to the slide member along the prop 4. A passing part 13 in parallel with the axis of the prop 4 is formed on either one side of the prop 4 and the slide member of the drilling machine side and projections 10 possible to pass the passing part 13 is provided on the other side. By passing the projection 10 on the passing part 13, the edge 21 provided on the drilling machine 20 is arrived at the work through the guide hole of the work clamp so that the work is drilled.