As symbionts of fungi and algae, lichens produce a variety of secondary products which pharmacological activities. This study aimed to investigate the anti-inflammatory activities of Heterodermia hypoleuca and its main compound, atraric acid. The results confirmed that atraric acid could regulating induced pro-inflammatory cytokine, nitric oxide, induced nitric oxide synthase and cyclooxygenase-2 expression by lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Means while, atraric acid down-regulated expression of phosphorylated IκB, ERK and nuclear factor kappa B (NFκB) signaling pathway to exhibit anti-inflammatory effects in LPS-stimulated RAW264.7 cells. Based on these results, the anti-inflammatory effect of atraric acid during LPS-induced endotoxin shock in a mouse model was confirmed. In the atraric acid treated-group, cytokine production was decreased in the peritoneum and serum, and each organ damaged by LPS-stimulation was recovered. These results show that atraric acid has an anti-inflammatory effect and its molecular mechanism may be involved in the inactivation of the ERK/NFκB signaling pathway, demonstrating its value as a potential therapeutic for inflammatory diseases.