Inflammation is natural protective response of the body tissue caused by various stimuli. Macrophages start and control the inflammatory response. Microalgae have high value of ingredients including carotenoids which are well known for anti-inflammatory properties and used for various products in functional food industries. A green microalgal, Tetraselmis species contains a various type of carotenoids such as lutein, violaxanthin, astaxanthin, fucoxanthin, α-carotene and β-carotene. Therefore, we studied whether carotenoids isolated from Tetraselmis sp. with different culture conditions in Raw 264.7 cells and zebrafish (Danio rerio) have an anti -inflammatory effect. Carotenoid extracts of natural seawater (NS) and magma seawater (MS) showed inhibitory activity of nitric oxide (NO) overproduction without toxicity. In addition, carotenoid extracts of NS and MS inhibited pro-inflammatory cytokines including tumor necrosis factor (TNF)-α, interleukin (IL)- 1β and IL-6. Inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2, which are inflammatory mediators also decreased by pretreatment of NS and MS. Carotenoid extracts of NS and MS pretreatment also reduced phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kB (NF-kB). In conclusion, the carotenoid extract of Tetraselmis sp. has an anti -inflammatory effect and can be potential industrial ingredient.