PURPOSE: To obtain the subject compd. from a source material which is easily available, by reacting each specified phenol and hydroxypropionaldehyde under specified conditions.

CONSTITUTION: A phenol expressed by formula I (R1, R2 are each H, 1-20C alkyl or the like) is reacted with a 3-hydroxypropionaldehyde expressed by formula III (R3, R4 are each R1) in the presence of a basic catalyst (preferably a dimethylamine or the like) at 90 to 230°C and 0.01 to 50 bar to obtain an aldehyde expressed by formula III of the purpose. Further, if necessary, the compd. of formula III is treated with hydrogen in the presence of a hydrogenation catalyst (preferably Raney nickel) at 0 to 250°C and 0.1 to 300 bar to obtain the propanol of the purpose expressed by formula IV. As for the compd. of formula I, 2-methyl-4-t-butylphenol or the like is preferably used, and as for the compd. of formula II, 2,2-dimethyl-3-hydroxypropanol or the like is preferably used.