Disclosed herein are an apparatus for producing liposomes and a method of producing liposomes by which it is made possible to produce liposomes under sterile conditions during the manufacturing process while monitoring in line the particle diameter of liposomes. The apparatus for producing liposomes includes a unit for regulating the particle diameter of liposomes, a supply flow channel for supplying the particle diameter regulating unit with a solution under processing containing a liposome-forming lipid, and a discharge flow channel for discharging from the particle diameter regulating unit a solution under processing containing liposomes, the supply flow channel having an input port through which the solution under processing containing the liposome-forming lipid is put into the supply flow channel, wherein the discharge flow channel has a first light transmitting part at least a portion of which is made of material transparent to light, and also has at least a first light transmittance measuring unit which measures the light transmittance of the solution under processing containing liposomes by directing light to the first light-transmitting part from the outside of the first light-transmitting part. A method of producing liposomes by use of the apparatus.
