Abstract: A probe opening forming apparatus 139 comprising: light detecting means 140 for detecting a quantity of a light transmitted from a tip portion of the probe through a light of the source 116, which is on contact with the tip portion of the probe; storage means 142 for previously storing information about relation of the quantity of the light transmitted from the tip portion of the probe and the size of the opening; calculating means 144 for obtaining the value of the light quantity for obtaining an opening having a desirable size based on the information stored in the storage means 142; and pressing control means 126 for controlling the press of the tip portion of the probe against the light detecting means through the pressing means 114 such that a light quantity detected by the light detecting means 140 is equal to the light quantity calculated from the calculating means 144.