To accurately perform probing even when an operating environmental temperature and the operation condition of a device differ.

A calibration system for generating a pseudo reception signal that is subjected to a specific delay and attenuation for a transmission signal to a transmission antenna 3 is provided, a transmission signal is discharged as an electronic wave from the transmission antenna 3, measurement using the calibration system is performed during measurement using an antenna system for receiving a reflection wave 9 from a buried object 8 as a reception signal, and measurement data being obtained from the actual antenna system based on the measurement data that are obtained from the calibration system are corrected.