A method for producing a 3,5,5-trimethylhexanoic acid composition comprising a synthesis step of synthesizing 3,5,5-trimethylhexanal by hydroformylation reaction of diisobutylene and oxo gas and synthesizing crude 3,5,5-trimethylhexanoic acid by subsequent oxidation reaction, and
- a purification step of purifying the crude 3,5,5-trimethylhexanoic acid,
- wherein the purification step includes a distillation step of distilling the crude 3,5,5-trimethylhexanoic acid, a water washing step of washing the 3,5,5-trimethylhexanoic acid obtained in the distillation step with water and a bubbling step of bubbling the 3,5,5-trimethylhexanoic acid obtained in the water washing step with an inert gas.