[en] For the denuclearization, nuclear activities must be reported and the reported documents must be confirmed through nuclear disarmament verification process. Sampling from undeclared area is an essential task of the verification to obtain information about the concealment of nuclear material. However, it is not possible to get the environmental radioactivity information of undeclared areas, so the safety of workers for sampling cannot be guaranteed. Therefore, before collecting samples, it is necessary to secure the information about radioactivity of the sampling region through the radiation measurement. In this study, we propose a compact gamma detection probe that can be transported by drones and distributed over a wide area in a short period of time. A plastic scintillator was applied to reduce weight and increase efficiency. In addition, the total weight and power consumption of the probe were optimized by applying a measurement method that counts photons generated from the scintillator. The performance of the probe was evaluated under the same dose conditions as the actual measurement environment. It was confirmed that the probe developed in this study exceeded more than twice the count value of background radiation at 25 meters. In addition, it was confirmed that the count value increased at a linear rate as the dose rate. As a result, it is possible to estimate the dose rate from the measured count value