[en] A measuring method and dose rate meter for β-ray absorbed dose independent of the β-ray maximum energy have been developed. To obtain constant dose sensitivity (counting rate per absorbed dose rate), a thin plastic scintillator is used as the detector, and the pulses selected by a single channel analyzer (SCA) are counted. The desirable pulse height distribution in obtaining a constant dose sensitivity is obtained with 2 mm thick scintillator. The lower level of discrimination and the window width of the SCA are chosen according to the epidermal thickness of tissue exposed to β-rays. The dose sensitivity of the absorbed dose rate meter is constant at 50 cps/(mrad/hr) +-15% for β-rays with maximum energy 0.4 -- 3.5 MeV (epidermal thickness 7 mg/cm²) and 0.3 -- 3.5 MeV (epidermal thickness 40 mg/cm²). The absorbed dose rate is given by multiplying the counting rate by a constant factor 2.0 x 10^-2 (mrad/hr)/cps. The lower limit of dose rate measurement is 1.7 x 10^-2 mrad/hr (7 mg/cm²) and 9.4 x 10^-3 mrad/hr (40 mg/cm²). (auth.)