[Problem] To provide: an ICG lipid derivative that can form a lipid-based particle that has an excellent stability and/or can selectively release a drug; and a lipid-based particle containing this ICG lipid derivative.

[Solution]A lipid-based particle comprising a compound represented by formula (A) below or a pharmaceutically acceptable salt thereof,

##STR00001##

wherein, R.sub.1 and R.sub.2 each independently represent (CH.sub.2).sub.kCONHR.sub.3; R.sub.3 represents a group selected from the group consisting of (CH.sub.2).sub.mOPO.sub.3.sup.CH.sub.2CH(CH.sub.2OCOR.sub.4)(OCOR.sub.5), branched-chain C.sub.14 to C.sub.40 alkyl, and branched-chain C.sub.14 to C.sub.40 alkenyl; R.sub.4 and R.sub.5 each independently represent straight-chain or branched-chain C.sub.13 to C.sub.21 alkyl or straight-chain or branched-chain C.sub.13 to C.sub.21 alkenyl; k represents an integer from 2 to 4; and m represents an integer from 2 to 4.

[Problem] To provide: an ICG lipid derivative that can form a lipid-based particle that has an excellent stability and/or can selectively release a drug; and a lipid-based particle containing this ICG lipid derivative.

[Solution]A lipid-based particle comprising a compound represented by formula (A) below or a pharmaceutically acceptable salt thereof,

##STR00001##

wherein, R.sub.1 and R.sub.2 each independently represent (CH.sub.2).sub.kCONHR.sub.3; R.sub.3 represents a group selected from the group consisting of (CH.sub.2).sub.mOPO.sub.3.sup.CH.sub.2CH(CH.sub.2OCOR.sub.4)(OCOR.sub.5), branched-chain C.sub.14 to C.sub.40 alkyl, and branched-chain C.sub.14 to C.sub.40 alkenyl; R.sub.4 and R.sub.5 each independently represent straight-chain or branched-chain C.sub.13 to C.sub.21 alkyl or straight-chain or branched-chain C.sub.13 to C.sub.21 alkenyl; k represents an integer from 2 to 4; and m represents an integer from 2 to 4.