1. A data generation device for generating data used in a detection process using a vision sensor, based on positions of three-dimensional models of a robot, the vision sensor and an object which are positioned in a virtual space, the data generation device comprising: a robot placement position designating part which designates a placement position of the robot in the virtual space based on a reference coordinate system defined in the virtual space; a vision sensor placement position designating part which designates a placement position of the vision sensor in the virtual space based on the reference coordinate system; a placement position storing part which stores the placement positions of the robot and the vision sensor; a positional relationship calculating part which calculates a positional relationship between a robot coordinate system defined in relation to the robot and a sensor coordinate system defined in relation to the vision sensor, based on the placement positions of the robot and the vision sensor; and a positional relationship storing part which stores the positional relationship between the robot coordinate system and the sensor coordinate system as data used in a detection process of the vision sensor.