A three-dimensional object printing apparatus comprising: a first robot supporting a head having a nozzle for discharging a liquid and changing a position and a posture of the head; a second robot supporting a three-dimensional workpiece (W) and changing a position and a posture of the workpiece; and a controller configured to control the first robot and the second robot, and to synchronize a liquid discharge operation of the head with an operation of the first robot, wherein the controller is configured to perform a first printing step of causing the head to discharge a liquid to a first region of the workpiece, while the controller is configured to control the first robot to cause the head to perform scanning along the first region, and in the first printing step, the controller is configured to control the second robot to fix the position and the posture of the workpiece in a first state, the three-dimensional object printing apparatus further comprising: a curing unit fixed to a base and configured to emit energy to cure or solidify the liquid discharged from the head, wherein after the first printing step is performed, the curing unit is configured to perform a first curing step of irradiating the liquid on the first region with energy, while the controller is configured to control the second robot to change relative positions and postures of the curing unit and the workpiece (W). a first robot supporting a head having a nozzle for discharging a liquid and changing a position and a posture of the head; a second robot supporting a three-dimensional workpiece (W) and changing a position and a posture of the workpiece; and a controller configured to control the first robot and the second robot, and to synchronize a liquid discharge operation of the head with an operation of the first robot, wherein the controller is configured to perform a first printing step of causing the head to discharge a liquid to a first region of the workpiece, while the controller is configured to control the first robot to cause the head to perform scanning along the first region, and in the first printing step, the controller is configured to control the second robot to fix the position and the posture of the workpiece in a first state, the three-dimensional object printing apparatus further comprising: a curing unit fixed to a base and configured to emit energy to cure or solidify the liquid discharged from the head, wherein after the first printing step is performed, the curing unit is configured to perform a first curing step of irradiating the liquid on the first region with energy, while the controller is configured to control the second robot to change relative positions and postures of the curing unit and the workpiece (W). a curing unit fixed to a base and configured to emit energy to cure or solidify the liquid discharged from the head, wherein after the first printing step is performed, the curing unit is configured to perform a first curing step of irradiating the liquid on the first region with energy, while the controller is configured to control the second robot to change relative positions and postures of the curing unit and the workpiece (W). <EOS>