[Problem] To provide a LELIA (Liposome-based Enzyme-Linked ImmunoAssay) method using recombinant proteoliposomes, wherein the baseline is sufficiently lowered, allowing the measurement of trace substances that were previously difficult to detect. [Solution] A method for measuring a membrane-protein-binding substance, said method being characterized by the provision of the following steps: (1) a container adsorption step in which recombinant proteoliposomes manufactured by fusing liposomes with recombinant budded baculoviruses expressing a membrane protein are added to a first container and adsorbed to the walls thereof； (2) a first washing step； (3) a membrane-protein-binding-substance binding step in which membrane proteins and a membrane-protein-binding substance are made to bind to each other in the liquid phase in the first container； (4) a second washing step； (5) a first antibody binding step in which primary antibodies that recognize the membrane-protein-binding substance are added and reacted with the membrane-protein-binding substance bound to the membrane proteins； (6) a third washing step； (7) a second antibody binding step in which enzyme-labeled secondary antibodies that bind to the first antibodies are added and reacted with the primary antibodies； (8) a fourth washing step； (9) a transfer step in which a solution is added, and after the recombinant proteoliposomes have become suspended therein, said solution is transferred to a second container； and (10) a detection step.L'objectif de la présente invention est de pourvoir à une méthode LELIA (dosage immunoenzymatique à base de liposomes) utilisant des protéoliposomes recombinés, caractérisée par une ligne de base suffisamment abaissée pour permettre la mesure de substances à l'état de traces qui étaient précédemment difficiles à détecter. Pour ce faire, la présente invention utilise un procédé de mesure d'une substance se liant à une protéine membranaire caractérisé par la mise en œuvre des étapes sui
