The present invention provides an aminopropylidene derivativerepresented by the formula (I), having excellent histamine receptorantagonisticaction, a compound which is useful as a pharmaceutical composition, especiallyas an active ingredient such as an antihistamine, having alleviated sideeffects inthe central nervous system, such as drowsiness. In the formula, R1 and R2,whichmay be identical or different, stand for a hydrogen, a substituted carbonyl, asubstituted carbonylalkyl, and acrylic acid with proviso that a case wherebothare hydrogen is excluded； R3 and R4, which may be identical or different,standfor hydrogen, an alkyl which may be substituted with phenyl, or the like； Astands for unsubstituted or an oxo； B stands for a carbon or an oxygen； one ofXand Y stands for a carbon and the other stands for a sulfur, a broken linepartstands for a single bond or a double bond, and a wavy line stands for cis-formand/or trans-form.
