Gear unit and robot

A gear unit, comprising:

• an inner shaft and an outer shaft concentrically arranged to make up two concentric output shafts;
• a first and a second input shaft extending in a direction orthogonal to the output shafts and operatively connected to the inner shaft and the outer shaft, respectively;
• and
• a stopper unit configured to limit a rotation angle of each of at least one of the output shafts,
• wherein the inner shaft includes an inner gear attached thereto and the outer shaft includes an outer gear attached thereto, the inner gear being arranged to face the outer gear, the first input shaft and the second input shaft being spaced apart from each other by a specified distance along an axial direction of the output shafts, the first input shaft including a first input gear meshing with the inner gear, the second input shaft including a second input gear meshing with the outer gear.