Yogyakarta Nuclear Area (YNA) is one of BATAN’s nuclear facility that has many nuclear facilities such as nuclear reactor, accelerator, irradiator, and waste management system. Due to nuclear accident is potentially occur, YNA has nuclear emergency response program and there is a preparedness system to support this program. Radiation monitoring system is one of utilization to acquire and record nuclear radiation exposure in the facility and its environment. An Internet of Thing based radiation area monitor was developed to improve the system not only to acquire the radiation exposure, but also to distribute the acquired data to the cloud server through the internet network. The distributed radiation data can be utilized to analyze nuclear emergence potential in the nuclear emergency response and preparedness system. The area monitor system was designed as sensor network that consists of Geiger Muller detector and high voltage power supply, signal conditioning system, and Arduino as counter and data processor. Data is acquired by a detector and it is transmitted to the server through wireless network using the node MCU communication module. The receiver station system was developed to acquire data from database server to display the radiation exposure in the environment and to identify radiological emergency status. Based on the chi square test stability method, the developed device has good stability which the probability of x 2 was obtained 0.75. The validation testing also was done using Sr-90 and x-ray spectrometer as radiation source, and the developed device has been compared using a standard survey-meter. The mean square error of this validation testing was 0.37 and 0.24 respectively for Sr-90 at two difference source distance, while for x-ray spectrometer source the mean square error value was 2.48. For further development, the system will be combined with a smart meteorological system to build the integrated data acquisition system for Nuclear and Radiological Emergency Preparedness System in Yogyakarta Nuclear Area.