This study intends to measure the level of maturity of the safety culture in an irradiator facility. The cultural model of safety will use the model developed by IAEA, namely 5 characteristics of the cultural safety which is divided into 37 attributes of safety culture. The level of maturity of the safety culture used in this study refers to the level of safety culture developed by Batan. This research uses descriptive analysis methods. The Analytic Hierarchy Process (AHP) approach will be used to analyze the level of maturity of safety culture and the Likert scale approach will be used to identify the characteristics of a strong safety culture and the characteristics of a safety culture that needs to be improved. From the results of the analysis with the AHP approach, the results of the assessment of the level of safety culture have not reflected the actual value. Based on research data, field facts and comparing with previous research in nuclear installation facilities and the assessment of nuclear safety inspector as an external perspective, researchers set the level of maturity of PT X's safety culture into the category of stage 2, namely good safety performance becomes an organizational objective. From the results of the analysis with the likert scale approach it is known that "Accountability for safety” is the most powerful characteristics and characteristics that need to be improved including “Leadership for safety”, “Safety is integrated into all activities” and “Safety is learning driven”. Researchers recommend PT X to start developing SMK3 so that the safety context does not only focus on radiation safety but can be broader into general safety, the need for documentation of the implementation of sharing sessions related to safety and organizing soft skills training.