PURPOSE: To provide a detecting system for an underground boring drill which can reduce the consumption of the battery of a transmitting device fixed to the underground boring drill and in addition, can prevent a device from becoming large.

CONSTITUTION: In the detecting system for the underground boring drill provided with the transmitting device 1 equipped to the drill 110 to bore a straight or curved hole under the ground and a receiving device 2 to be used on the ground, the transmitting device 1 is provided with a detecting part to detect the angle of the drill 110, a generating part to generate a transmission signal by intermitting the signal of single frequency in accordance with the detected angle, and a transmitting part to transmit this transmission signal toward a ground surface, and the receiving device 2 is provided with a receiving part to receive the signal from the transmitting device 1, a processing part to check the intermittence of the received reception signal and calculate the angle of the underground boring drill, and simulataneously, check the intensity of the continuous part of the reception signal and calculate the depth of the drill 110, and a displaying part to display a calculated result.