A workpiece model is created based on three-dimensionally measured data obtained by performing a three-dimensional measurement on a working space in which the workpieces are loaded in bulk. Holding data including a holding position of the workpiece model and a posture of a holding unit of a robot are set by setting a model coordinate system. The setting of the model coordinate system and the setting of the holding data are repeated while sequentially changing the posture of the workpiece, and multiple pieces of holding data are stored such that the multiple pieces of holding data correspond to the workpiece models. A three-dimensional search process is performed on the obtained three-dimensionally measured data, and an operation of the holding unit of the robot is controlled based on the holding data set to the workpiece model.