As the importance of Knowledge Management System (KMS) in the military increases, Republic of Korea Army (ROK Army) developed Army Knowledge Portal. Although the members in the military are encouraged to use the portal, few members currently use it. This study was conducted to find variables to predict the user’s intention to use the portal, which contributes to activating the use of Army Knowledge Portal in the army. On the basis of Technology Acceptance Model (TAM), ten variables such as perceived ease of use, general information security awareness, information security awareness, expectation for external rewards, expectation for relationships, sense of self-worth, attitude toward compliance with security policy, attitude toward knowledge sharing, intention of non-combat knowledge sharing, and intention of combat knowledge sharing were considered as independent variables. 105 participants on active duty who currently use or have experience to use the portal participated in this study. The results indicated that general information security awareness and information security awareness increases compliance with the information security policy. In addition, the attitude toward knowledge sharing is enhanced by expectations for relationship and sense of self-worth. Based on the results, the authors propose the need for policy alternatives to reinforce the reward system and security policy, which activates the use of Knowledge Portal Service for ROK Army.