Balancer mechanism for rotating shaft

A balancer mechanism for a rotating shaft for alleviating unbalanced torque acting on the rotating shaft that is freely rotationally supported by a shaft support member via a bearing member, from a member that is supported by the rotating shaft;

• wherein there are provided an assistance torque generation device for generating an assistance torque that mutually cancels out at least a part of the unbalanced torque, and a reaction force generation device on an opposite side of the rotating shaft from the assistance torque generation device;
• the assistance torque generation device comprising a cam member that is fixed to the rotating shaft, a cam follower member that contacts against and follows the cam member, and a biasing device for applying assistance torque to the rotating shaft via the cam member by biasing the cam follower member toward the cam member;
• wherein the reaction force generation device is configured for generating a balancing moment on the rotating shaft to mutually cancel out a tilting moment that tilts the rotating shaft, wherein the tilting moment tilts the rotating shaft in a direction away from the assistance torque generation device, around the bearing member as a center, as a result of the biasing force of the biasing device.