Abstract: The present invention provides novel cyclopropachromen-carboxylic acid derivatives having an antagonistic activity against metabotropic glutamate receptors and its pharmaceutically acceptable salts. Cyclopropachromen-carboxylic acid derivatives and its pharmaceutically acceptable salts represented by the following general formula (1): ##STR1## ?wherein A denotes an oxygen atom, hydroxyimino group, an alkyloxyimino group having 1 to 5 carbon atoms, or the group .dbd.N--O--(CH.sub.2).sub.n -NR.sup.1 R.sup.2 (where n represents an integer of 2 to 8, and each of R.sup.1 and R.sup.2 independently represents a hydrogen atom or alkyl group having 1 to 5 carbon atoms, respectively); B denotes the group --COOR.sup.3 (where R.sup.3 represents a hydrogen atom or alkyl group having 1 to 5 carbon atoms) or the group --CONR.sup.4 R.sup.5 (where R.sup.4 and R.sup.5 independently represent a hydrogen atom, alkyl group having 1 to 5 carbon atoms, alkenyl group having 2 to 5 carbon atoms and an aminoalkyl group.