Robot system and robot working method

A robot system comprising:

• a robot configured to perform a predetermined work with respect to a workpiece placed on at least one carriage of one or more carriages moving along a predetermined runway;
• a synchronous movable body configured to move along the predetermined runway synchronously with movement of the at least one carriage, the synchronous movable body comprising a position detector configured to detect a position of the at least one carriage on the predetermined runway;
• and
• a controller configured to control the robot to perform the predetermined work with respect to the workpiece placed on the at least one carriage synchronously with the movement of the at least one carriage based on the detected position of the at least one carriage on the predetermined runway.