A laser radar system that is capable of remotely detecting oil spills, in the daytime and at night, in sea water has been developed. The system employs the second harmonic and fourth harmonic of a repetitively Q-switched Nd:YAG laser as the light sources and a gated optical multichannel analyzer as a high speed detection device. The results show that the comparison of backscattering spectra obtained from different samples enables us to detect and characterize oil spills in sea water. Raman backscattering and backscattered fluorescence of kerosene, light oil, heavy oil, and sea water have been investigated both in the laboratory and in the harbor of Seto Inland Sea of Japan by using the laser radar system described above. The SNR of this laser radar system for the detection of Raman backscattering of kerosene and fluorescence of oil is also described.