AbstractThis paper discusses a highly precise method of measurement for the attenuation of a coaxial cable using a short test‐piece. The proposed method is used to compose an open‐ended resonator by the coaxial cable and to determine the attenuation from the resonant characteristics. To realize a highly accurate measurement using a very short test‐piece, the end effect of the cable must be corrected. A correction formula is presented, which by experiment, is verified as useful. The end effect in the proposed measurement is one order of magnitude less than that in the short‐circuit resonant method, which has been used in the past as the method measurement for the attenuation of the short test‐piece cable. It is shown that if the test‐piece is longer than a certain value, the measurement can be performed without considering the end effect. The measurement accuracy of 0.2 percent and the repeatability of 0.1 percent are realized by the proposed method. The upper limit of the cable attenuation that can be measured by the proposed method is discussed. When the resonant characteristics are measured by the half‐amplitude width, the upper limit is 7.6 dB, indicating that a wide range of attenuations can be measured. The proposed method is then applied to the measurement of the attenuation‐pressure characteristics of the submarine coaxial cable verifying the usefulnes