PURPOSE: To provide a cross-section detection device for a covering place which accurately detects a plurarity of adjacent steel pipes buried in soil.

CONSTITUTION: A transmitting antenna 6 is given a single detection waveform and a receiving antenna 7 receives reflected or transmitted waves so that the cross section of a hidden place corresponding to the time between transmission of electromagnetic waves from the transmittijng antenna 6 and outputs from the receiving antenna can be detected. A detection waveform given to the transmitting antenna 6 has rising and falling waveforms. The rising waveform has a small temporal change rate and has its level gradually decreasing with the lapse of time, so that outputs from the receiving antenna 7 do not vibrate, in other words, they have a waveform which does not cause ringing. This constitution allows objects in a plurarity of adjacent positions provided in a covering place to be accurately detected based on temporal differences.