1. A robot picking system, comprising: a robot that picks up a work in a stocker accommodating a plurality of works; a control device that controls an operation of the robot; and an image acquiring device that acquires image data including information related to the plurality of works, wherein the control device comprises a candidate data generating unit that generates candidate data including information of candidate works that are candidates of a picking-up target using the image data, and a target work selecting unit that selects a target work that is a picking-up target from the candidate works using the candidate data.