To detect the posture and position of an underground excavator without use of cables for transmitting signals and control it in accordance with the detected posture and position.

A TV camera 13, a clinometer 14, a displacement sensor 15, a directional correction cylinder 16, an electromagnetic valve 17 for directional correction, etc., are equipped in a pilot pipe 11. Microwave transmitting and receiving units 18, 19 and antennas 22, 23 are installed in the pilot pipe 11 and the excavating board 21 of the departure device 20 respectively. A control unit 27 is installed on the ground. In this case, the frequency of microwave ranges 1-100GHz.