A thiopyran derivative represented by the following formula (I) or (I'), or the salt thereof. ##STR1## wherein A is S or --CH.dbd.CH--; the dotted line indicates that the bond may be either present or absent; Z and Z' are typically ##STR2## L is an ethylene or trimethylene group; Y is CH or N; n is 2; B is a carbonyl group; m is 0 or 1; D is a phenyl group; and E.sub.1 and E.sub.2 are hydrogen atoms. These compounds exhibit a strong serotonin-2 blocking action and highly safe. Some compounds also exhibit an .alpha..sub.1 -blocking action and therefore are useful as an antihypertensive agent with less side effects. Thus, the thiopyran derivatives are useful as drugs for the treatment of circulatory diseases in general such as hypertension, ischemic heart disease, cerebrovascular disturbance, and peripheral circulatory disturbance.