PURPOSE: To obtain the titled compound in high yield, by using an alkali- containing alcohol, etc., as a solvent and a lanthanide element, etc., as a cocatalyst in oxidizing m-hydroxybenzyl alcohol with oxygen in the presence of platinum or palladium based catalyst.

CONSTITUTION: m-Hydroxybenzyl alcohol is oxidized with oxygen or an oxygen containing gas in the presence of a platinum and/or palladium based catalyst to produce m-hydroxybenzaldehyde useful as an intermediate for perfumes, medicines, etc. In the process, an alkali-containing 1W4C alcohol or mixed solvent of an alkali containing alcohol-water is preferably used as a solvent and a lanthanide element, e.g. cerium, samarium, europium, etc., or a compound thereof is present in the above-mentioned reaction system to suppress formation of m-hydroxybenzoic acid as a by-product. Thereby the aimed compound can be industrially and advantageously obtained from the above-mentioned raw material capable of producing the aimed compound at a relatively low cost in high yield.