[Problem]To provide a biodegradable compound having a structure decomposed in a cell, lipid particles containing the compound, and a pharmaceutical composition comprising the lipid particles.[Solution]The compound of the embodiment is represented by the formula (1): P—；[X—；R—；Y—；R′；-Q]2 (1). In the formula,P is an alkyleneoxy having an ether bond,X is a divalent linking group having a tertiary amine structure,R is a divalent linking group,R′； is a single bond or a C1 to C6 alkylene, andQ is a liposoluble vitamin residue, a sterol residue, or a C12 to C22 aliphatic hydrocarbon group. The structure of the compound contains at least one biodegradable group. From the compound in combination with other lipids such as a lipid capable of reducing aggregation, lipid particles can be formed. Further, the compound can be used for a pharmaceutical composition to deliver an activator into cells.
