A drilling apparatus includes: a drill rotatable about a center axis and capable of advancing and retracting along the axis; and a pressing unit for pressing a work in an advancing direction of the drill. The drilling apparatus advances the drill while rotating the drill about the center axis to form a hole in the work, in a state in which the work is pressed by the pressing unit. A pressing force applied on the work by the pressing unit is set to a predetermined pressing force based on machining reaction applied to the drill from the work during drilling and the pressing force causing deformation of the work in the advancing direction of the drill. The predetermined pressing force can suppress deformation of the work and displacement of the drill due to the machining reaction. The machining reaction and the pressing force are calculated beforehand in a drilling test.