PURPOSE: To enable accurate analysis of the underground construction based on data of high reliability by arranging detector/recorders for terrestrial magnetism and earth current at a plurality of points to perform a multi-collation processing of outputs thereof.

CONSTITUTION: Sensor sections 1W4 of a measuring apparatus are respectively provided with terrestrial magnetism and earth current detectors, 5-channel signal conditioners for adjusting data signals of five magnetic field/electric field components and data transmitting/receiving sections. The sensor sections are each connected to a data processing section 6 with an optical fiber cable 5 while made portable. The processing section 6 containing a computer performs a triple collation processing of desired 3-point data immediately among those obtained simultaneously by the sensor sections 1W4.