An experimental study to treat and reuse oily wastewater generated from the automobile-components manufacturing industry was performed. The feasibility of using an ultrafiltration (UF) membrane and ozone treatment to reuse oily wastewater was investigated. The UF membrane system (capacity, 5 t/d) was employed to treat two kinds of degreasing wastewater and cutting oil wastewater. Flux behavior and organic removal strongly depended on the type of oily wastewater. The UF permeates from the degreasing wastewater could be reused as make-up water. However, the cutting oil formulated with the UF permeates had very different characteristics such as emulsion size and foaming ratio because surfactant existed excessively in the UF permeates. Partial oxidation of surfactants in UF permeates using ozone makes it unable to change the emulsion size, foaming ratio and refractory index, and thus, possible to reuse the UF permeates as process water.