A novel chromone derivative having a strong antitumor activity of the general formula: ##STR1## wherein R.sup.1 is an unsaturated alkyl or cycloalkyl group having 3 to 7 carbon atoms; R.sup.2 is hydrogen atom or a halogen atom; R.sup.3 is hydrogen atom or a lower alkyl group; and X is carboxyl group, or its salt, ester or amide.