To securely judge the breakage of a drill and clinging of cutting chips with a simple structure.

An air jetting port 3 and a pressure detecting port 4 are provided so as to be opposed with each other on each side of a drill D which moves ahead or back in the direction of an axis L while being held by a chuck C of a processing device. The air jetting port 3 is supplied with high pressure air from an air supply 5, and a pressure at the pressure detecting port 4 is detected by pressure detecting means 12. When the drill D after completing processing moves back from a work W, if the pressure detected by the pressure detecting means 12 is in the range of 0.01 to 0.04 kgf/cm2, it is judged that the drill D is in a normal condition; if the detected pressure is 0.04 kgf/cm2 or more, it is judged that the drill D is broken; or if the detected pressure is 0.01 kgf/cm2 or less, it is judged that clinging of cutting powder occurs on the drill D.