A robot system according to one or more embodiments may include a robot, and a control part. The robot may include one or more joints driven by an electric motor, and can hold a wafer by a holding part. The control part gives commands to the robot for control. When the robot holds and transports the wafer with the holding part, the control part performs, based on information about the electric motor, at least one of the following: determining whether slippage has occurred between the holding part and the wafer; and estimating an amount of slippage of the wafer relative to the holding part.