PURPOSE: To obtain the subject compound in high selectivity with a reduced amount of an organic diphosphine compound to be used.

CONSTITUTION: In producing the objective hydroxybutyraldehyde compound by hydroformylation of allyl alcohol in the presence of a rhodium complex catalyst with an antimony compound as ligand, 0.4-1.2 (esp. 0.8-1.0) equivalent, per gram atom of the rhodium in said catalyst, of an organic diphosphine compound of formula I (formula II represents a substituted or non-substituted 3 to 5-element cyclic structure with the elements consisting of C or C plus O atoms; R1-R4 are each aryl or alkyl) or formula III (formula IV represents a substituted or non-substituted five-membered cyclic structure with the elements making up the ring consisting of C plus N atoms; R1'-R4' are each aryl or alkyl), e.g. trans-4,5-bis(diphenylphosphinemethyl)-2,2-dimethyl-1,3-dioxolan, is added to the reaction system.