Abstract: The stack gripper is provided in a robot to pick up and transport a box stack includes a fixing frame connected to a robot, a fixing panel provided at a lower portion of the fixing frame, a horizontal pressing member provided at the lower portion of the fixing frame to face the fixing panel and to be moved horizontally on the fixing frame, a vertical pressing member provided at a lower portion of the fixing frame to be moved vertically, and a fork member provided at the fixing frame to face the vertical pressing member and to be moved horizontally on the fixing frame.