In this study, a beta monitoring sensor was developed as a part of basic research for quantitative beta monitoring underwater, and its performance was evaluated using a calibration source. A beta detection sensor was manufactured by using SiPM(silicon photomultiplier) and CaF 2 :Eu, YAG:Ce, YAP:Ce scintillator. A large-area light guide was introduced to improve beta-ray detection efficiency. As calibration sources, the Beta source 90 Sr, which is the main fission product of a nuclear accident, and the gamma source Cs are used. In the performance evaluation, it is confirmed that scintillator CaF 2 :Eu gives the highest beta-ray detection response. Compared to gamma ray, beta-ray detection responsivity and detection efficiency are verified. Therefore, this study is expected to contribute to basic research in the development of an underwater beta-ray monitoring system. Received: Aug. 16, 2016, Revised: Sep. 19, 2016, Accepted: Sep. 27, 2016 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/ licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.