The objective of this study was to enhance the lipid productivity in microalga Tetraselmis sp. through the salinity variation during cultivation. When marine alga Tetraselmis sp. was cultivated in a wide range of salinities, 0 through 70 practical salinity unit (PSU), enriched with F/2 medium, relatively low salinities below 35 PSU resulted in higher growth rates and lipid productivities under both N-deficient and -sufficient conditions, as compared to high salinities above 45 PSU. Nitrogen limitation did not stimulate lipid production in this species. Although high salinity increased lipid content, overall lipid productivities were lowered than those under low salinity conditions due to the decreased biomass production. When the salinity shifted from 35 to 22 PSU during cultivation, total lipid content increased from 20 to 26 (w/w) % within four days, and no significant change of fatty acids composition was observed.