(-)-DHM2EQ, which is useful as an antitumor agent and an anti-inflammatory agent, can be directly obtained by optically resolving (.+-.)-DHM2EQ using an optically active column packed with an optical resolving agent containing, for example, amylose tris(3,5-dimethylphenylcarbamate) as an active ingredient. The (-)-DHM2EQ obtained by optical resolution using the optically active column or pharmacologically acceptable salt thereof is useful as a pharmaceutical composition for improving various symptoms.