A plate member reversing system for sequentially reversing and transferring a plurality of plate members, the plate member reversing system comprising: a reversing device, onto which the plate member held by an upstream-side transfer/placing robot is transferred and placed in a horizontal position, for performing a reversing operation of reversing upper and lower surfaces of the plate member, while the transferred and placed plate member is being held with its upper surface in an open state; transfer device configured to perform a transfer operation of receiving the reversed plate member from the reversing device and transferring the received plate member in a reversed state and in a horizontal position; and a control device which executes control that enables the upstream-side transfer/placing robot, the reversing device and the transfer device to operate intermittently, wherein: the transfer device is a belt conveyor; the reversing device is configured to reverse the plate member and to place the plate member onto the belt conveyor to deliver the plate member to the belt conveyor; characterized in that the plate member reversing system further comprises the upstream-side transfer/placing robot including an arm and configured to perform an upstream-side transfer/placing operation of sequentially holding, and transferring and placing the plurality of plate members by using the arm; and the control device is configured such that while the upstream-side transfer/placing robot is caused to perform the upstream-side transfer/placing operation in a state in which the reversing operation of the reversing device is stopped, the control device causes the transfer device to perform the transfer operation in sync with the upstream-side transfer/placing operation. a reversing device, onto which the plate member held by an upstream-side transfer/placing robot is transferred and placed in a horizontal position, for performing a reversing operation of reversing upper and lower surfaces of the plate member, while the transferred and placed plate member is being held with its upper surface in an open state; transfer device configured to perform a transfer operation of receiving the reversed plate member from the reversing device and transferring the received plate member in a reversed state and in a horizontal position; and a control device which executes control that enables the upstream-side transfer/placing robot, the reversing device and the transfer device to operate intermittently, wherein: the transfer device is a belt conveyor; the reversing device is configured to reverse the plate member and to place the plate member onto the belt conveyor to deliver the plate member to the belt conveyor; characterized in that the plate member reversing system further comprises the upstream-side transfer/placing robot including an arm and configured to perform an upstream-side transfer/placing operation of sequentially holding, and transferring and placing the plurality of plate members by using the arm; and the control device is configured such that while the upstream-side transfer/placing robot is caused to perform the upstream-side transfer/placing operation in a state in which the reversing operation of the reversing device is stopped, the control device causes the transfer device to perform the transfer operation in sync with the upstream-side transfer/placing operation. the transfer device is a belt conveyor; the reversing device is configured to reverse the plate member and to place the plate member onto the belt conveyor to deliver the plate member to the belt conveyor; characterized in that the plate member reversing system further comprises the upstream-side transfer/placing robot including an arm and configured to perform an upstream-side transfer/placing operation of sequentially holding, and transferring and placing the plurality of plate members by using the arm; and the control device is configured such that while the upstream-side transfer/placing robot is caused to perform the upstream-side transfer/placing operation in a state in which the reversing operation of the reversing device is stopped, the control device causes the transfer device to perform the transfer operation in sync with the upstream-side transfer/placing operation.