A polyrotaxane, comprising a composite molecular structure formed of an axle molecule and a plurality of cyclic molecules clathrating the axle molecule, wherein the polyrotaxane satisfies at least one of requirements and: requirement: a side chain having a secondary or tertiary hydroxyl group is introduced into at least part of the cyclic molecule of the polyrotaxane; wherein the side chain having the secondary or tertiary hydroxyl group comprises a structure represented by the following formula: wherein, Q is formed of at least one kind selected from structures represented by the following formulas (Q-1), (Q-2) and (Q-3): wherein, G is a straight-chain alkylene group or alkenylene group having 1 to 8 carbon atoms; a branched-chain alkylene group or alkenylene group having 3 to 20 carbon atoms; an alkylene group or alkenylene group formed by replacement a part of the alkylene group or alkenylene group by a -O- bond, a -NH- bond, a -SO- bond or a -SiO- bond; or an alkylene group formed by replacement of a part of hydrogen of the alkylene group by at least one kind selected from the group consisting of a hydroxyl group, a carboxyl group, an acyl group, a phenyl group, a halogen atom and an olefin group, and when a plurality of G exist, each G may be a same group or a different group, and n 1, n 2, n 3 are each independently an integer from 1 to 200, and when Q is formed of two or more kinds selected from the formulas (Q-1), (Q-2) and (Q-3), G constituting (Q-1) to (Q-3) may be a same group or a different group, a total of n 1, n 2 and n 3 is an integer from 1 to 200, X is an alkylene group or alkenylene group having 2 to 20 carbons, or an alkylene group or alkenylene group formed by replacement of a part of the alkylene group or alkenylene group by a -O- bond or a -NH-bond; R 3 and R 4 are each independently selected from hydrogen, a straight-chain alkyl group having 1 to 6 carbon atoms or a branched-chain alkyl group having 1 to 6 carbon atoms, excluding a group in which R 3 and R 4 are simultaneously hydrogen; and R 5 is carbon or sulfur; and requirement: a side chain having a group represented by the following formula: -A (wherein, A is an organic group having 1 to 10 carbon atoms and contains at least one hydroxyl group) is introduced into at least part of the cyclic molecule of the polyrotaxane; and a pKa of a hydroxyl group of a compound represented by the following formula: H-A is 6 or more and less than 14. requirement: a side chain having a secondary or tertiary hydroxyl group is introduced into at least part of the cyclic molecule of the polyrotaxane; wherein the side chain having the secondary or tertiary hydroxyl group comprises a structure represented by the following formula: wherein, Q is formed of at least one kind selected from structures represented by the following formulas (Q-1), (Q-2) and (Q-3): wherein, G is a straight-chain alkylene group or alkenylene group having 1 to 8 carbon atoms; a branched-chain alkylene group or alkenylene group having 3 to 20 carbon atoms; an alkylene group or alkenylene group formed by replacement a part of the alkylene group or alkenylene group by a -O- bond, a -NH- bond, a -SO- bond or a -SiO- bond; or an alkylene group formed by replacement of a part of hydrogen of the alkylene group by at least one kind selected from the group consisting of a hydroxyl group, a carboxyl group, an acyl group, a phenyl group, a halogen atom and an olefin group, and when a plurality of G exist, each G may be a same group or a different group, and n 1, n 2, n 3 are each independently an integer from 1 to 200, and when Q is formed of two or more kinds selected from the formulas (Q-1), (Q-2) and (Q-3), G constituting (Q-1) to (Q-3) may be a same group or a different group, a total of n 1, n 2 and n 3 is an integer from 1 to 200, X is an alkylene group or alkenylene group having 2 to 20 carbons, or an alkylene group or alkenylene group formed by replacement of a part of the alkylene group or alkenylene group by a -O- bond or a -NH-bond; R 3 and R 4 are each independently selected from hydrogen, a straight-chain alkyl group having 1 to 6 carbon atoms or a branched-chain alkyl group having 1 to 6 carbon atoms, excluding a group in which R 3 and R 4 are simultaneously hydrogen; and R 5 is carbon or sulfur; and requirement: a side chain having a group represented by the following formula: -A (wherein, A is an organic group having 1 to 10 carbon atoms and contains at least one hydroxyl group) is introduced into at least part of the cyclic molecule of the polyrotaxane; and a pKa of a hydroxyl group of a compound represented by the following formula: H-A