A hair cosmetic composition which gives a feeling of light-sliding smoothness and a not-heavy feeling of not-unruliness to hair. The hair cosmetic composition contains a both terminally long-chain alkylamino group-modified polyorganosiloxane having a viscosity at 25° C. of 1,000 to 5,000,000 mPas, represented by the formula: MDxD′yM wherein M is a siloxy unit represented by the formula: R1R22SiO0.5, D is a siloxy unit represented by the formula: R22SiO, and D′ is a siloxy unit represented by the formula: R2R3SiO, where R1 is an alkyl group having 12 to 50 carbon atoms, R2 is a substituted or unsubstituted hydrocarbon group having 1 to 6 carbon atoms, R3 is 3-aminopropyl group and/or N-(2-aminoethyl)-3-aminopropyl group, x is a value of 1 to 2,000, and y is a value of 1 to 50.