This paper describes an automated drug screening system for Ca 2+-activated K+ channel proteins (BK channel). BK channels are pharmacological targets for the treatment of stroke. We have been developing multiple lipid bilayer membranes (BLMs) system for reconstituting the membrane proteins . In this study, the osmotic pressure in the proteoliposomes was controlled to induce the vesicle fusion. As a result, we succeeded in simultaneous reconstitution of BK channels in the BLMs array using an injection robot (Fig. 1). Moreover, the channel inhibition behavior was examined using a K+ channel blocker. Since our method is applicable for multi-type of proteoliposomes, we believe that the system can be used as a high-throughput screening (HTS) system for membrane-protein-based drug discovery.