To screen high lipase activity marine yeast, 39 samples from seawater and sea slug were collected. The marine yeasts were isolated through adopting Rhodamine preliminary screening plate and secondarily screening with shake flask loading fermentation medium. A higher lipase activity yeast was obtained and identified as Pichia guilliermondii based on the results of routine and molecular identification. Lipase produced by P. guilliermondii was partially purified by (NH₄)₂SO₄ precipitation and immobilized on silica. Lipolytic activities of the enzyme in free as well as immobilized crude enzyme were compared in different pH, temperature, metal ions and detergent and enzyme inhibitors. A sharp decrease in lipolytic activity was observed in case of free and immobilized crude enzyme at 50, 55 and 55 °C, respectively. The lipase activity of both free and immobilized crude extracts was inhibited when incubated with Na⁺, K⁺, Ag⁺, Zn²⁺, EDTA, PMSF, SDS and Tween80. Both the free and immobilized crude lipase forms were found to have a stimulatory effect in the presence of Mn²⁺, Cu²⁺ , Mg²⁺, Ca²⁺, Ba²⁺, Fe³⁺ and Triton X-100 showed an inhibitory effect on the activity of free as well as immobilized crude lipase.