A robot system having a vision sensor. The robot system includes a robot; a robot controlling section for controlling an operation of the robot; an imaging section provided on the robot and obtaining image data of a working environment of the robot; an image processing section for processing the image data obtained in the imaging section; a vision controlling section for controlling the imaging section and the image processing section to cause execution of obtaining the image data, transmitting the image data thus obtained, and processing the image data; and a communication network to which the robot controlling section, the image processing section and the vision controlling section are connected. The robot controlling section, the image processing section and the vision controlling section are incorporated into a common robot control unit, the imaging section is connected to the image processing section through the communication network, and the vision controlling section causes a transmission of the image data obtained in the imaging section through the communication network to the image processing section.