Objectives : This experimental study was performed to investigate the effect of herbal eye drops(Sean-tang, Jinpi-san, Tangpo-san, Copitdis Rhizoma) on Staphylococcus aureus keratitis. Methods : After administering various herbal eye drops on Staphylococcus aureus, I measured MIC and the size of inhibition zone. MIC was measured by dropping from 20 to $50{mu}{ell}$ according to density. Anti-bacterial potency was measured by the size of inhibition zone with change of volume under 2 days culture condition. Also continuous antibacterial potency of herbal eye drops was measured by the size of inhibition zone according to 2 days and 6 days culture each under the $50{mu}{ell}$condition. Results : 1. MIC on Staphylococcus aureus in Sean-tang, Jinpi-san and Tangpo-san was 100%, $20{mu}{ell}$. 2. MIC on Staphylococcus aureus in Coptidis rhizoma was 10%, $30{mu}{ell}$. 3. MIC on Staphylococcus aureus in Cravit was 0.1%, $50{mu}{ell}$. 4. Under the 2 days culture condition, the size of inhibition zone on Staphylococcus aureus by volume for Sean-tang was 12.0mm in $50{mu}{ell}$, Jinpi-san was 19.0mm in $50{mu}{ell}$, Tangpo-san was 15.0mm in $50{mu}{ell}$, Coptidis rhizoma was 32.7 mm in $50{mu}{ell}$ and Cravit was 31mm in $50{mu}{ell}$, Coptidis rhizoma showed the highest anti-bacterial potency. 5. Under the $50{mu}{ell}$ condition, the size of inhibition zone on Staphylococcus aureus by 2 and 6 culture days for Sean-tang was 12.0mm, Jinpi-san was 19.0mm, Tangpo-san was 15.0mm, Coptidis rhizoma was 32.7mm and Cravit was 31.0 mm, which showed sameness anti-bacterial potency in 2 days and 6 days. Conclusions : The present author think that the herbal eye drops can be used to cure Staphylococcus aureus keratitis and if further study is performed, the use of the herbal eye drops will be valuable and beneficial in the clinical medicines.