A hair processing composition contains an alkoxysilane (1)； an organic acid； and water and has a pH in a range of from 2 to 5.A method for processing hair includes mixing while stirring the above-described hair processing composition and allowing a silanol compound (2) produced through hydrolysis of the alkoxysilane (1) represented by general formula (1) to penetrate into the hair.A method for processing hair further includes applying to hair an acidic aqueous solution or an alkaline aqueous solution after the silanol compound (2) has penetrated into the hair to accelerate the polymerization of the silanol compound.R1pSi(OR2)4-p (1)R1pSi(OH)n(OR2)4-p-n (2)wherein R1 and R2 represent a C1-C6 alkyl group or a C2-C6 alkenyl group, p represents an integer of from 0 to 3, and n represents an integer of not less than 1 and not more than (4−p).
