An economical process for producing (2- and/or 1-)cyclohexenyl methyl ketones which are intermediates for the synthesis of &agr;- or &bgr;-damascone. In the presence of a catalyst, a 3-cyclohexenyl methyl ketone represented by the following formula (1a): wherein, R1, R2 and R3 each independently represents a hydrogen atom or a methyl group and at least two of R1, R2 and R3 are methyl groups, is isomerized.