A rehabilitation device comprising: an operation unit operated by a patient under rehabilitation; an operation amount detection unit arranged to detect an operation amount of the operation unit; a driving unit arranged to apply torque to the operation unit; a control unit arranged to control driving of the driving unit; and a movement state detection unit arranged to detect a movement state of a moving part of the patient wherein the control unit is arranged to calculate a target value of the operation amount to be performed on the operation unit based on the movement state detected by the movement state detection unit and a predetermined movement model and to control the driving unit so that the operation amount detected by the operation amount detection unit follows the calculated target value of the operation amount; the device further comprising an external force detection unit arranged to detect an external force applied to the operation unit wherein the control unit is arranged to calculate a target value of a virtual operation amount to be performed on the operation unit based on the movement state detected by the movement state detection unit and the predetermined movement model, to calculate the target value of the operation amount based on the calculated target value of the virtual operation amount and the external force detected by the external force detection unit, and to control the driving unit so that the operation amount detected by the operation amount detection unit follows the calculated target value of the operation amount; wherein the movement state detection unit is a myogenic potential sensor arranged to detect a myogenic potential of the moving part of the patient and the control unit is arranged to calculate a rotation angle target value of a virtual wrist joint by calculating a muscular strength of the moving part based on the myogenic potential detected by the myogenic potential sensor and then solving the predetermined movement model based on the calculated muscular strength; and characterized in that the control unit is arranged to perform impedance control, based on the calculated rotation angle target value of the virtual wrist joint and the external force detected by the external force detection unit, and to calculate a rotation angle target value of the wrist joint, the impedance control including a damping coefficient and a stiffness coefficient. an operation unit operated by a patient under rehabilitation; an operation amount detection unit arranged to detect an operation amount of the operation unit; a driving unit arranged to apply torque to the operation unit; a control unit arranged to control driving of the driving unit; and a movement state detection unit arranged to detect a movement state of a moving part of the patient wherein the control unit is arranged to calculate a target value of the operation amount to be performed on the operation unit based on the movement state detected by the movement state detection unit and a predetermined movement model and to control the driving unit so that the operation amount detected by the operation amount detection unit follows the calculated target value of the operation amount; the device further comprising an external force detection unit arranged to detect an external force applied to the operation unit wherein the control unit is arranged to calculate a target value of a virtual operation amount to be performed on the operation unit based on the movement state detected by the movement state detection unit and the predetermined movement model, to calculate the target value of the operation amount based on the calculated target value of the virtual operation amount and the external force detected by the external force detection unit, and to control the driving unit so that the operation amount detected by the operation amount detection unit follows the calculated target value of the operation amount; wherein the movement state detection unit is a myogenic potential sensor arranged to detect a myogenic potential of the moving part of the patient and the control unit is arranged to calculate a rotation angle target value of a virtual wrist joint by calculating a muscular strength of the moving part based on the myogenic potential detected by the myogenic potential sensor and then solving the predetermined movement model based on the calculated muscular strength; and characterized in that the control unit is arranged to perform impedance control, based on the calculated rotation angle target value of the virtual wrist joint and the external force detected by the external force detection unit, and to calculate a rotation angle target value of the wrist joint, the impedance control including a damping coefficient and a stiffness coefficient.