Abstract: The gear tester includes (a) a first driving shaft driven by a motor and having a first driving gear fixed thereto; (b) a second driving shaft parallel with the first driving shaft and having a second driving gear fixed thereto; (c) a pair of intermediate gears meshing with each other, via which the first and second driving shafts are operably connected to each other; (d) a frame rotatably supporting the pair of intermediate gears, the frame being movable in a transverse direction so that a rotation phase difference is generated between the first and second driving gears depending upon the movement of the frame; and (e) a pair of test gears meshing with each other, one of which is fixed to the first driving shaft and the other of which is fixed to the second driving shaft. By moving the frame, a torque load is applied to test gears.