To surely collect chips even though a through-hole having a small inner diameter is formed, and to form a hole having a smooth inner surface.

An air passage 34 having one end part which is opened to a surface 33 having a distance R from an center axis P of a shaft 33 in a plan including the center axis O of a spindle 11 and the center axis P of the shaft 32, and the other end part which can be connected to an external compressed air source is provided in a pressure foot 30. Blow-out passages 40A, 40B having one end part opened to the inner surfaces of through-holes 39A, 39B and the like, and the other end opened to a surface 38 having the distance R from the center axis P are provided in a circuit board retaining piece 38. Further, if a though-hole positioned at where a drill 26 penetrates, is, for example, the through hole 39A, the blow-out passage 40A is connected to the supply passage 34.