SrBi$_2$Ta$_2$$O_{9}$ thn films were etched in inductively coupled Cl$_2$/CF$_4$/Ar plasma. THe maximum etch rate was 1060 $AA$/min at a Cl$_2$/(Cl$_2$+CF$_4$+Ar)=0.2. The 20% additive Cl$_2$ into CF$_4$/Ar plasma decreased carbon and fluorine radicals, but increased Cl radicals. Sr was effectively removed by reacting with Cl radical because the boiling point of SrCl$_2$(125$0^{circ}C$) is lower than that of SrF$_2$(246$0^{circ}C$). The chemical reactions on the etched surface were studied with x-ray photoelectron spectroscopy and secondary ion mass spectrometry. The etching profile was evaluated by using scanning electron microscopy.y.