A novel 2,4-dihydroxyadipic acid derivative of the formula:
wherein R¹ and R⁴ are the same or different and each a hydrogen atom, an alkyl group, an aralkyl group, an aryl group or a silyl group, and R² and R³ are the same or different and each a hydrogen atom or a protective group of a hydroxy group or together form a ring, which is useful as a common intermediate in the synthesis of HMG-CoA reductase inhibitor.