To provide a non-contact depth detecting method of a drilled hole suitable for an electric hand drilling apparatus.

Whether or not a drill bit has been pressed against a workpiece is detected by a position sensor 8 which detects the displacement of a spindle 6. An ultrasonic distance sensor 11 installed in a housing 2 radiates ultrasonic waves toward the workpiece and receives reflected waves of the ultrasonic waves in order to measure the distance to the workpiece. The distance measured at the start of machining by the drill bit (datum position) is memorized. The distance measured during machining (current position) is compared with a datum position to detect a feed distance that is a drilled depth.