This study aims to 1) find out the Implementation of the Inventory Internal Control System according to COSO at PT. Zikrul Hakim Bestari Surabaya Branch. 2) knowing the effectiveness of the Implementation of the Inventory Internal Control System at PT. Zikrul Hakim Bestari Surabaya. The research method used is qualitative. Research on research that is descriptive and in general will utilize examination. Qualitative research does not plan to reach speculation over the determination but rather centers on the depiction of the article being noticed. The results of the research obtained Overall internal control over supplies at PT. Zikrul Hakim Bestari has been running effectively but not yet efficiently because several components are not following the components of the control system according to COSO such as position traps and human resource standards that are not under their fields in control activities.