Robot system and method for producing to-be-processed material

A robot system (100) includes a robot (101). The robot (101) includes a holder (10) to hold a first workpiece from among workpieces stored in a stocker (102). A sensor (103) performs shape recognition of the workpieces stored in the stocker (102) and detects a holding state of the first workpiece held by the robot (101). A controller (104) controls the sensor (103) to perform the shape recognition of the workpieces stored in the stocker (102), controls the robot (101) to hold the first workpiece based on the shape recognition and transfer the first workpiece to a particular position in a sensor area of the sensor (103), controls the sensor (103) to detect the holding state of the first workpiece held by the robot (101), and controls the robot (101) to place the first workpiece in a predetermined position or posture based on the detected holding state.