Robot system, method for controlling robot, and method for producing to-be-processed material

A robot system comprising:

• a robot;
• a fitting member holder mounted to a distal end of the robot to hold a fitting member;
• a receiver member configured to receive the fitting member;
• a position determination member disposed at a fixed position relative to the receiver member;
• and
• a robot controller configured to control the robot, the robot controller comprising:
• a position identifying device configured to bring at least one of the robot, the fitting member, and the fitting member holder into contact with the position determination member with the fitting member holder holding the fitting member, and configured to identify a fitting position based on a position of the contact as a reference position;
• and
• a fitting control device configured to control the robot to fit the fitting member into the receiver member at the fitting position.