This study was conducted to develop m automatic pot-seedling transplanter for plant factory. The transplanter consists of a gripper, row-spacing control device, nursing tray transfer system, growing trough transfer system, and gripper moving device. The gripper picks up pot-seedling. The gripper moving device moves the gripper between nursing tray and growing-flat. Nursing trays are moved to workspace by the nursing tray transfer system. The growing trough transfer system was developed to move growing trough to workspace. The row-spacing control device was used to adjust the distance between adjacent plants traversely. The results of this study are as follows. The transplanting capacity of the developed transplanter was 7.1 seconds per cycle or 1.18 second per pot-seedling. Successful planting was 98.9% without seedlings and 95.8% with seedlings.