A robot system for assisting a patient in standing up and/or sitting down is provided. The robot system includes the following elements. A drive mechanism executes a drive pattern for assisting the patient in standing up and/or sitting down. An instruction input device receives an instruction to cause the drive mechanism to execute the drive pattern. A state acquirer acquires an execution state of the drive mechanism which is executing the drive pattern. A controller decides whether or not to cause the drive mechanism to execute the instruction received by the instruction input device, on the basis of the execution state acquired by the state acquirer, and controls the driving of the drive mechanism.