Abstract: It is difficult to check the suitability of a radio anechoic room as a measuring environment, even when countermeasures for preventing reflection of electromagnetic waves and blocking electromagnetic waves are taken against the radio anechoic room and incidental equipment disposed therein, for example. Depending on the circumstances, measurement reliability is decreased when the measurement is taken without recognizing that these countermeasures are insufficient. Therefore, there is a demand for a device that can easily and quickly check whether a measuring environment, such as a radio anechoic room, or a measuring system is suitable for measurement.