Just like UV radiation, heat increases collagen degradation and accumulation of abnormal elastin fiber and this is termed thermal skin aging. Dunaliella salina (DS), a green alga, is known for its beta-carotene accumulation, having various applications in the health and nutritional products. However, the effects of DS on heat-induced skin aging remain unexplored. In this study, we performed anti-thermal aging tests of the ethanol extract of DS (DSE). We measured the cellular levels of type I procollagen and MMP-1 using ELISA in human dermal fibroblast cells after heat shock. DSE reduced the expression of MMP-1 protein and increased the expression of type I procollagen. In addition, DSE upregulated the mRNA expression of HSP47 reduced by heat shock, which is involved in collagen synthesis. Also, DSE reduced the expression of inflammation mediator (TGF-β, IL-12, etc). We demonstrate that DSE regulates the heat-induced solar elastosis through the regulation of tropoelastin and fibrillin-1, two major proteins of elastic fibers, and MMP-12 expression. These results suggest that DSE may be effective for preventing thermally induced skin aging.