Abstract: The purification method of an aldehyde compound of the present invention includes a step of neutralizing a reaction solution containing an aldehyde compound by adding water and a base compound to the reaction solution, and a step of distilling the neutralized reaction solution, in which the reaction solution is obtained by reacting a compound represented by the following Formula (a1) or (a2) with hydrogen and carbon monoxide in the presence of a metal compound of groups 8 to 10 and a phosphorus compound, the phosphorus compound is represented by Formula (R1O)3P, and the base compound is at least one kind selected from among carbonate and hydrogen carbonate of metals of group I on the periodic table and carbonate and hydrogen carbonate of metals of group II on the periodic table.