A method for producing a (2-formyl-1-alkenyl)cyclopropane compound represented by the formula (1): ##STR00001## wherein R.sup.1 and R.sup.2 are the same or different, and independently represent a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted aryl group or an optionally substituted aralkyl group, which comprises reacting a formylcyclopropane compound represented by the formula (3): ##STR00002## wherein R.sup.1 is the same as defined above, with an aldehyde compound represented by the formula (4): ##STR00003## wherein R.sup.2 is the same as defined above, in the presence of a base.