A rotational torsion tester comprising:- a first drive shaft for attachment to an end of a workpiece, wherein the first drive shaft rotates about a predetermined rotation axis; a second drive shaft for attachment to the other end of the workpiece, wherein the second drive shaft rotates about the predetermined rotation axis; a load applying unit comprising: a first electric motor for driving and rotating the first drive shaft to apply a torsional load to the workpiece; a first bearing unit that supports the load applying unit to be rotatable about the predetermined rotation axis; and a rotation drive unit having a second electric motor that drives the second drive shaft and the load applying unit to rotate in phase; wherein the load applying unit includes a frame having a cylindrical shaft part into which the first drive shaft is inserted, the frame being supported by the first bearing unit at the cylindrical shaft part, wherein the cylindrical shaft part includes a pair of first bearings (1123, 1124) which are disposed to be away from each other in an axial direction and rotatably support the first drive shaft; and a torque sensor, disposed between the pair of first bearings (1123, 1124), and attached to the first drive shaft in the cylindrical shaft part for detecting torsional load; wherein by causing the second electric motor to rotate the workpiece via the first drive shaft and the second drive shaft and by causing the load applying unit to give a phase difference to rotations of the first drive shaft and the second drive shaft, a load is applied to the workpiece. a first drive shaft for attachment to an end of a workpiece, wherein the first drive shaft rotates about a predetermined rotation axis; a second drive shaft for attachment to the other end of the workpiece, wherein the second drive shaft rotates about the predetermined rotation axis; a load applying unit comprising: a first electric motor for driving and rotating the first drive shaft to apply a torsional load to the workpiece; a first bearing unit that supports the load applying unit to be rotatable about the predetermined rotation axis; and a rotation drive unit having a second electric motor that drives the second drive shaft and the load applying unit to rotate in phase; a first electric motor for driving and rotating the first drive shaft to apply a torsional load to the workpiece; a first bearing unit that supports the load applying unit to be rotatable about the predetermined rotation axis; and a rotation drive unit having a second electric motor that drives the second drive shaft and the load applying unit to rotate in phase; wherein the load applying unit includes a frame having a cylindrical shaft part into which the first drive shaft is inserted, the frame being supported by the first bearing unit at the cylindrical shaft part, wherein the cylindrical shaft part includes a pair of first bearings (1123, 1124) which are disposed to be away from each other in an axial direction and rotatably support the first drive shaft; and a torque sensor, disposed between the pair of first bearings (1123, 1124), and attached to the first drive shaft in the cylindrical shaft part for detecting torsional load; wherein by causing the second electric motor to rotate the workpiece via the first drive shaft and the second drive shaft and by causing the load applying unit to give a phase difference to rotations of the first drive shaft and the second drive shaft, a load is applied to the workpiece.