PURPOSE: To obtain a liposome, composed of a long-chain active amide and a lipid capable of forming the liposome, useful as drug carriers, immulological analytical reagents, etc., and capable of modifying surfaces.

CONSTITUTION: The objective substance is obtained by mixing ≤ 50 wt.% compound expressed by the formula [R1 is hydrophobic group; R2 and R3 are organic group (including H) or R2 and R3 may be linked to form a ring or double bond; X and Y are O or S] with a liposome constituent material and preparing a liposome according to a well-known method. The existing lipids except phosphatidylethanolamine and phosphatidylserine which are used as the constituent material of the liposome are cited as the constituent material of the liposome. Examples thereof are egg yolk lecithin and dipalmitoylphosphatidylcholine. Surface-modified liposomes immobilizing various substrates can be readily obtained by mixing the aforementioned lioposome with the substrates (e.g. amino acid-containing peptides or antigen- or antibody- containing proteins) having amino groups and/or thiol groups.