A process for producing an aldehyde compound of the invention comprising: reacting a compound represented by the following formula (a1) or (a2) with a hydrogen and a carbon monoxide in a presence of a compound containing a metal belonging to Groups 8 to 10 and a phosphorous compound so as to satisfy the following conditions (1) and (2) to synthesize an aldehyde compound; wherein the condition (1) is that a content of a metal included in the compound containing a metal belonging to Groups 8 to 10 is 0.01 ppmmol to 300 ppmmol with respect to 1 mol of the compound represented by the formula (a1) or (a2), and wherein the condition (2) is that a molar ratio represented by the phosphorous compound (mol)/the metal (mol) is 100 or more;