A hair styling method comprising the steps of: applying a hair cosmetic composition containing the following component to the hair: Component: an organopolysiloxane, wherein at least two silicon atoms in an organopolysiloxane segment constituting a main chain of the organopolysiloxane are bound to poly(N-acylalkyleneimine) segments consisting of repeating units represented by the following general formula via alkylene group containing hetero atom: wherein R 1 is a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, an aralkyl group, or an aryl group; and n is 2 or 3; wherein the number-average molecular weight (MW OX) of the poly(N-acylalkyleneimine) segment is from 1,600 to 3,500, as measured by gel permeation chromatography in accordance with the method as described in the present specification, wherein the mass ratio of the organopolysiloxane segments (a) constituting the main chain to the poly(N-acylalkyleneimine) segments (b) [i.e., a/b] is from 42/58 to 58/42, wherein [a/b] by mass is a value obtained from analyzing the integration ratio between alkyl groups or phenyl groups in the organopolysiloxane segments and methylene groups in the poly(N-acylalkyleneimine) segments by nuclear magnetic resonance ( 1 H-NMR) after dissolving the organopolysiloxane in deuterium chloroform to provide a solution of 5% concentration by mass, wherein the weight-average molecular weight MWg of the organopolysiloxane segments between adjacent poly(N-acylalkyleneimine) segments is from 1,600 to 3,500; MWg being calculated by the following formula: MWg = Csi × MWox 100 − Csi wherein Csi is the content ratio of the organopolysiloxane segment constituting the main chain, and wherein the weight-average molecular weight MWsi of the organopolysiloxane segment constituting the main chain is from 7,000 to 100,000, as measured by gel permeation chromatography in accordance with the method as described in the present specification; forming the hair style at a hair temperature of 50°C or higher; and subsequently cooling the hair temperature to lower than 50°C to fix the formed hair style. Component: an organopolysiloxane, wherein at least two silicon atoms in an organopolysiloxane segment constituting a main chain of the organopolysiloxane are bound to poly(N-acylalkyleneimine) segments consisting of repeating units represented by the following general formula via alkylene group containing hetero atom: wherein R 1 is a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, an aralkyl group, or an aryl group; and n is 2 or 3; wherein the number-average molecular weight (MW OX) of the poly(N-acylalkyleneimine) segment is from 1,600 to 3,500, as measured by gel permeation chromatography in accordance with the method as described in the present specification, wherein the mass ratio of the organopolysiloxane segments (a) constituting the main chain to the poly(N-acylalkyleneimine) segments (b) [i.e., a/b] is from 42/58 to 58/42, wherein [a/b] by mass is a value obtained from analyzing the integration ratio between alkyl groups or phenyl groups in the organopolysiloxane segments and methylene groups in the poly(N-acylalkyleneimine) segments by nuclear magnetic resonance ( 1 H-NMR) after dissolving the organopolysiloxane in deuterium chloroform to provide a solution of 5% concentration by mass, wherein the weight-average molecular weight MWg of the organopolysiloxane segments between adjacent poly(N-acylalkyleneimine) segments is from 1,600 to 3,500; MWg being calculated by the following formula: MWg = Csi × MWox 100 − Csi wherein Csi is the content ratio of the organopolysiloxane segment constituting the main chain, and wherein the weight-average molecular weight MWsi of the organopolysiloxane segment constituting the main chain is from 7,000 to 100,000, as measured by gel permeation chromatography in accordance with the method as described in the present specification; forming the hair style at a hair temperature of 50°C or higher; and subsequently cooling the hair temperature to lower than 50°C to fix the formed hair style.