Along with the increasing use of information and communication technology, information security becomes something fundamental. BATAN as one of the government agencies currently wants to increase the security awareness of its employees. As a national nuclear agency, information security awareness is crucial, as it relates to the safety of the society. This study aims to know how the relationship between the three variables of knowledge, attitude and behavior in BATAN. A nuclear agency has a special characteristics of information security because it has a higher standard related to information security than other institutions. By knowing how the interaction of these three variables, is expected to know how to improve employee behavior toward information security. The arrangement of research variables and instruments is done through Focus Group Discussion (FGD). FGD results were then compiled into questionnaires, distributed to 420 Batan employees. From 420 questionnaire, 381 was returned and processed using regression analysis. As a result, it is known that employee knowledge of information security affects employee attitudes to information security, employee attitudes to information security affect employee behavior in reducing security risks, and employee knowledge of information security affects employee behavior in reducing security risks.