Compound or salt thereof and lipid particles

Lipid particles comprising:

• a compound represented by Formula (1) or a salt thereof;
• a sterol;
• and
• a lipid having a nonionic hydrophilic polymer;
• wherein in the formula, X represents —NR1— or —O—,
• R1 represents a hydrogen atom, a hydrocarbon group having 6 to 24 carbon atoms, or a group represented by R21-L1-R22—, R21 represents a hydrocarbon group having 1 to 24 carbon atoms, L1 represents —O(CO)O—, —O(CO)—, —(CO)O—, —O—, or a group represented by the following formula,
• R22 represents a divalent hydrocarbon linking group having 1 to 18 carbon atoms,
• R2 and R3 each independently represent a hydrogen atom, a hydrocarbon group having 3 to 24 carbon atoms, or a group represented by R31-L2-R32—, R31 represents a hydrocarbon group having 1 to 24 carbon atoms, L2 represents —O(CO)O—, —O(CO)—, —(CO)O—, —O—, or a group represented by the following formula,
• R32 represents a divalent hydrocarbon linking group having 1 to 18 carbon atoms,
• R4, R5, R6, R7, R8, R9, R10, R11, and R12 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 R4 and R5, R10 and R5, R5 and R12, R4 and R6, R5 and R6, R6 and R7, R6 and R10, R12 and R7, and R7 and R8 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 —NR45R46, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaryl group, or a group represented by —O(CO)O—R41, —O(CO)—R42, —(CO)O—R43, or —O—R44, R41, R42, R43, R44, R45, and R46 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 —NR45R46, or a group represented by —O(CO)O—R41, —O(CO)—R42, —(CO)O—R43, or —O—R44, R41, R42, R43, R44, R45, and R46 each independently represent a hydrocarbon group having 1 to 18 carbon atoms,
• a, b, c, and d each independently represent an integer of 0 to 3, a+b is equal to or greater than 1, and c+d is equal to or greater than 1.