A method of forming a via hole reaching a bonding pad in a wafer having a plurality of devices on the front surface of a substrate and bonding pads formed on each of the devices by applying a pulse laser beam from the rear surface side of the substrate, wherein when a pulse laser beam having a spot diameter which satisfies D/2≦d≦D−2 μm (wherein a diameter of the via hole to be formed is represented as D and a spot diameter of the pulse laser beam is represented as d) is applied in such a manner that the periphery of the spot moves along the inner circumference of the via hole to be formed, the pulse laser beam is applied at an angle of 120 to 180° from the previous application position.