A marine microorganism producing biosurfactant was isolated from the oil polluted coast of Chung-Mu in Korea, and was identified as Pseudomonas sp.. It produced the biosurfactanl and its optimum culture conditions for pH and salt concentration were 8.0 and 3.0%, respectively. The productivity of biosurfactant from this strain was affected by the nitrogen source used. For the oil resolvability of the biosurfactant, the residual oil in the culture broth with 2% Kuwait crude oil at each time of 48, 96, and 132hr was investigated by gas chromatography. As result of this experiment, it was verified that the biosurfactant acted on C10-C14, of Kuwait crude oil and so the oil was decomposed. The biosurfactant isolated from the supernatant was purified by adsorption to Amberliter XAD-7 and followed by gel chromatography (Sephadex G-100) and HPLC. The purified biosurfactant showed a high value of emulsifying activity at $40^{circ}C$ and the emulsifying stability was maintained at the temperature range of $30^{circ}C$∼$60^{circ}C$. The purified biosurfactant reduced the interfacial tension of Kuwait crude oil remarkably and showed improved dispersing ability compared to those of commercial surfactants such as Tween 80, Tween 60 and SDS.