To provide a rotating shaft of a rotation system capable of efficiently transmitting the rotating torque of rotating shafts of two motors to a rotating shaft of a load.

A rotating shaft of a rotation system includes: a rotating shaft of a first motor provided adjacent to a load to rotate the load; and a rotating shaft of a second motor provided next to the first motor to rotate the load. The rotating shaft of the first motor has a cylindrical shape and is connected to a rotating shaft of the load, and the rotating shaft of the second motor penetrates through an inner periphery of the rotating shaft of the first motor and is connected to the rotating shaft of the load.