Thymus magnus is an endemic (Ulleung Island) species in Korea. This plant is used as diaphoretics and carminatives in traditional medicine. In the literature, few scientific assays were realized on this species, such as antibiotic (Streptococcus pneumoniae, Staphylococcus aureus, Salmonella enteritidis, and S. typhimurium) and antifungal activities. In order to clarify whether essential oil of T. magnus have pharmacological effects, anti-inflammatory, sedative, anti-depressant, analgesic, and sleep-prolonged effects were investigated using animal models. From this study, the following conclusions were attained; 1) Essential oil of T. magnus did not show any acute toxicity on mice when orally administered at the dose of 2-3 g/kg body weight. 2) Essential oil of T. magnus possessed strong anti-inflammatory activity, similar to that of a positive control prednisolone. 3) Essential oil of T. magnus had excellent analgesic activity, comparable to that of aspirin. 4) The essential oil of T. magnus possessed strong sleep-prolonged effect on pentobarbital induced-sleep test in mice model. 5) In the hot plate test, the essential oil of T. magnus had moderate effect. 6) And the essential oil of T. magnus had no significant effects in forced-swimming test and open-field test.