A work robot system including a conveying apparatus that conveys an object in one direction; a robot that performs a predetermined task on a target portion of the object being conveyed by the conveying apparatus, a movement amount detector that sequentially detects the movement amount of the object moved by the conveying apparatus, and a force detector that detects a force generated by contact between a tool supported by the robot and the object. Then, when the predetermined task is performed, a controller performs force control based on a value detected by the force detector while performing control of the robot by use of information about the position of the target portion and a value detected by the movement amount detector.