A data generation device and a detection simulation system, capable of executing offline simulation using a vision sensor, without calibration for associating the vision sensor with the robot. The device has: a placing part which places three-dimensional models of a robot, a vision sensor and an object in a virtual space; a robot placement position designating part and a vision sensor placement position designating part which designate placement positions of the robot and the vision sensor in the virtual space, respectively, based on a reference coordinate system defined in the virtual space; a placement position storing part which stores the placement positions; a positional relationship calculating part which calculates a positional relationship between a robot coordinate system and a sensor coordinate system; and a positional relationship storing part which stores the positional relationship as data used in a detection process of the vision sensor.