To provide a new method for producing an alkyl- or aryloxyacetaldehyde by which an easily available raw material can be used and the final product can be provided by simple and few steps.

This method for producing the alkyl- or aryloxyacetaldehyde represented by formula (I) [wherein, R is an alkyl, an aryl, a heteroaryl, an alkalyl, an alkylheteroaryl, an aralkyl, a heterocycle or an alkylheterocycle] comprises reacting a compound represented by the formula (II): R-OM (II) [wherein, M is an alkali metal or an alkaline earth metal] with a compound represented by formula (III) [wherein, R1 and R2 are each an alkyl group or form an alkylene group by bonding to each other; and X is a halogen atom] to provide a corresponding dialkyl acetal represented by formula (IV), and cleaving the resultant acetal to provide the required alkyl- or aryloxyacetaldehyde.