To provide a robot which has a motor section small in size, light in weight, and reduced in noise, and a balancer small in size, and achieves energy saving and weight reduction thereof.

According to the configuration of the robot, when the balancer such as a plate spring, which can obtain a large stress upon generation of a small displacement, is provided on a rotatable arm in the vicinity of a joint, the balancer exerts a strong assisting stress at a lower angle at which a large rotating torque is required. Therefore when the arm is assisted to rotate up to 60 degrees by combining the motor and a balancer device with each other, a torque not more than 1/2 of conventionally required torque is required to rotate the arm through the entire rotation zone, to thereby achieve minimization of the motor and weight reduction of the robot. Further by providing a dust removing means for the balancer, in addition to shielding of a joint section by a magnetic fluid, high cleanliness of the balancer is maintained. The balancer device is applicable to assisting various types of vertically rotatable devices in a clean room.