The invention provides a liposome composition which is obtained by mixing a water miscible organic solution in which a phospholipid and cholesterol are contained at a total concentration of 100 to 200 w/v% in a water miscible organic solvent with a first aqueous phase solution in an amount of 3/1 to 12/1 in terms of volume ratio to the water miscible organic solution thereby obtaining an emulsion in which the total concentration of the phospholipid and cholesterol in the resulting mixed phase is 15 to 50 w/v% followed by subjecting the emulsion to external solution exchange with a second aqueous phase solution wherein an ion gradient is formed between an aqueous phase in an internal region of a liposome membrane comprising the first aqueous phase solution and an aqueous phase in an external region of the liposome membrane comprising the second aqueous phase solution and a drug can be introduced in a high encapsulation amount. The invention also provides a liposome preparation which has long lasting controlled release properties while maintaining a clinically sufficient effective concentration and is suitable for subcutaneous administration and so on.
