Abstract: A component of ethylacetate extract of Terminalia muelleri Benth. leaves, was found to inhibit Staphyloccoccus aureus and Methicillin-resistant Staphylococcus aureus growth therefore, the aims of this study were to investigate the effect of the active components on morphology of bacteria cell which was observed by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Tetracycline HCl, penicillin G and vancomycin HCl were used as reference antibiotic. The active component at twice of the MIC caused shrinkage and thinning of the cell wall. The cell damage pattern which is caused by the active compound was similar to the damage caused by vancomycin HCl. It was explained that the antibacterial target of action of the active compound was inhibit the synthesis of the cell wall.