[en] The characteristics of various detectors based on field measurement and the characteristics of measuring points are described. The detectors used for the measurement were a NaI(T1) scintillation detector, an organic scintillation survey meter, a high pressure ionization chamber and a spherical NaI(T1) scintillation spectrometer. Field measurement was made at 8 points in Ehime Prefecture for the period from September, 1980, to March, 1982. The measurement was made at the points of 1 m high from the ground surface. Comparison among the detectors was made. The results of measurement with the spherical NaI(T1) detector and the high pressure ionization chamber were in good agreement. The dispersion of the measured data with the ion chamber was the smallest. The result of measurement with the NaI(T1) scintillation detector showed high counting efficiency for low energy gamma-ray. The efficiency of the organic scintillation survey meter decreased at higher energy. Comparison among the measured results at the measuring points was made. The time variation of the measured results showed a maximum in February, 1982, which may be an effect of rainfall. As the results of this study, it can be said that it is necessary to pay attention to the use of a NaI(T1) scintillation detector for the measurement of environmental radiation. Because of the large dispersion of the measured data, comparison measurement is necessary for the organic detector. (Kato, T.)