A re-calibration method and device for a three-dimensional visual sensor of a robot system, whereby the work load required for re-calibration is mitigated. While the visual sensor is normal, the visual sensor and a measurement target are arranged in one or more relative positional relations by a robot, and the target is measured to acquire position/orientation information of a dot pattern etc. by using calibration parameters then held. During re-calibration, each relative positional relation is approximately reproduced, and the target is again measured to acquire feature amount information or position/orientation of the dot pattern etc. on the image. Based on the feature amount data and the position information, the parameters relating to calibration of the visual sensor are updated. At least one of the visual sensor and the target, which are brought into the relative positional relation, is mounted on the robot arm. During the re-calibration, position information may be calculated using the held calibration parameters as well as the feature amount information obtained during normal operation of the visual sensor and that obtained during the re-calibration, and the calibration parameters may be updated based on the calculation results.