A printed board drilling method and a printed board machining apparatus capable of improving machining quality, such as improving positional accuracy of holes and true roundness of machined holes, and improving work efficiency by minimizing a runout of the tip of a drill. An extension of the drill extending out of a spindle when the drill is held by the spindle is defined in advance per type or mode of use of each drill. One drill is selected among a plurality of drills corresponding to a shape of holes to be drilled in the printed board and the spindle holds the drill so that the selected drill extends out of the spindle by the extension corresponding to the selected drill. Then, the move of the spindle with respect to the printed board is controlled and the selected drill is rotationally driven by the spindle to drill the printed board.