The object is to provide a novel LXR.beta. agonist that is useful as a preventative and/or therapeutic agent for atherosclerosis; arteriosclerosis such as those resulting from diabetes; dyslipidemia; hypercholesterolemia; lipid-related diseases; inflammatory diseases that are caused by inflammatory cytokines; skin diseases such as allergic skin diseases; diabetes; or Alzheimer's disease. The solving means is a 1,3-dihydroisobenzofuran derivative represented by the following general formula (1) or salt thereof, or their solvate. ##STR00001##