A lipid composition comprising: a lipid represented by Formula or a salt thereof; a nonionic lipid; a lipid having a nonionic hydrophilic polymer structure; and a nucleic acid, wherein the lipid composition contains or does not contain a zwitterionic lipid, and in a case where represents a molar ratio in percentage of the lipid represented by Formula or a salt thereof to total lipids constituting the lipid composition, and represents a molar ratio in percentage of the zwitterionic lipid to the total lipids constituting the lipid composition, and satisfy 40 < - ≤ 90, in the formula, X represents -NR 1 - or -O-, R 1 represents a hydrogen atom, a hydrocarbon group having 6 to 24 carbon atoms, or a group represented by R 21 -L 1 -R 22 -, R 21 represents a hydrocarbon group having 1 to 24 carbon atoms, L 1 represents -O O-, -O -, - O-, -O-, or a group represented by the following formula, R 22 represents a divalent hydrocarbon linking group having 1 to 18 carbon atoms, R 2 and R 3 each independently represent a hydrogen atom, a hydrocarbon group having 3 to 24 carbon atoms, or a group represented by R 31 -L 2 -R 32 -, R 31 represents a hydrocarbon group having 1 to 24 carbon atoms, L 2 represents -O O-, -O -, - O-, -O-, or a group represented by the following formula, R 32 represents a divalent hydrocarbon linking group having 1 to 18 carbon atoms, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R 11, and R 12 each independently represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms that may be substituted, groups in any one or more pairs among R 4 and R 5, R 10 and R 5, R 5 and R 12, R 4 and R 6, R 5 and R 6, R 6 and R 7, R 6 and R 10, R 12 and R 7, and R 7 and R 8 may be linked to each other to form a 4- to 7-membered ring which may contain an O atom, a substituent on the alkyl group having 1 to 18 carbon atoms that may be substituted is a hydroxyl group, a carboxyl group, an amino group represented by -NR 45 R 46, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a group represented by -O O-R 41, -O -R 42, - O-R 43, or -O-R 44, R 41, R 42, R 41, R 44, R 45, and R 46 each independently represent a hydrocarbon group having 1 to 18 carbon atoms, a substituent on the substituted or unsubstituted aryl group and on the substituted or unsubstituted heteroaryl group is an alkyl group having 1 to 18 carbon atoms, a hydroxyl group, a carboxyl group, an amino group represented by -NR 45 R 46, or a group represented by -O O-R 41, -O -R 42, - O-R 43, or -O-R 44, and R 41, R 42, R 43, R 44, R 45, and R 46 each independently represent a hydrocarbon group having 1 to 18 carbon atoms, and a, b, c, and d each independently represent an integer of 0 to 3, a + b is 1 or more, and c + d is 1 or more. a lipid represented by Formula or a salt thereof; a nonionic lipid; a lipid having a nonionic hydrophilic polymer structure; and a nucleic acid, wherein the lipid composition contains or does not contain a zwitterionic lipid, and in a case where represents a molar ratio in percentage of the lipid represented by Formula or a salt thereof to total lipids constituting the lipid composition, and represents a molar ratio in percentage of the zwitterionic lipid to the total lipids constituting the lipid composition, and satisfy 40 < - ≤ 90, in the formula, X represents -NR 1 - or -O-, R 1 represents a hydrogen atom, a hydrocarbon group having 6 to 24 carbon atoms, or a group represented by R 21 -L 1 -R 22 -, R 21 represents a hydrocarbon group having 1 to 24 carbon atoms, L 1 represents -O O-, -O -, - O-, -O-, or a group represented by the following formula, R 22 represents a divalent hydrocarbon linking group having 1 to 18 carbon atoms, R 2 and R 3 each independently represent a hydrogen atom, a hydrocarbon group having 3 to 24 carbon atoms, or a group represented by R 31 -L 2 -R 32 -, R 31 represents a hydrocarbon group having 1 to 24 carbon atoms, L 2 represents -O O-, -O -, - O-, -O-, or a group represented by the following formula, R 32 represents a divalent hydrocarbon linking group having 1 to 18 carbon atoms, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R 11, and R 12 each independently represent a hydrogen atom or an alkyl group having 1 to 18 carbon atoms that may be substituted, groups in any one or more pairs among R 4 and R 5, R 10 and R 5, R 5 and R 12, R 4 and R 6, R 5 and R 6, R 6 and R 7, R 6 and R 10, R 12 and R 7, and R 7 and R 8 may be linked to each other to form a 4- to 7-membered ring which may contain an O atom, a substituent on the alkyl group having 1 to 18 carbon atoms that may be substituted is a hydroxyl group, a carboxyl group, an amino group represented by -NR 45 R 46, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a group represented by -O O-R 41, -O -R 42, - O-R 43, or -O-R 44, R 41, R 42, R 41, R 44, R 45, and R 46 each independently represent a hydrocarbon group having 1 to 18 carbon atoms, a substituent on the substituted or unsubstituted aryl group and on the substituted or unsubstituted heteroaryl group is an alkyl group having 1 to 18 carbon atoms, a hydroxyl group, a carboxyl group, an amino group represented by -NR 45 R 46, or a group represented by -O O-R 41, -O -R 42, - O-R 43, or -O-R 44, and R 41, R 42, R 43, R 44, R 45, and R 46 each independently represent a hydrocarbon group having 1 to 18 carbon atoms, and a, b, c, and d each independently represent an integer of 0 to 3, a + b is 1 or more, and c + d is 1 or more.