A method for determining a torque of an auger of a pile driving rig , wherein the pile driving rig comprises an auger rotator including a frame of the auger rotator, a driving motor , a frame of the driving motor and a lever arm , wherein the method comprises determining the torque of the auger by measuring at least one of the following items in structures of the pile driving rig : a force effected by the torque on at least one point in the structures of the pile driving rig , or an elongation caused by the force effected by the torque on at least one point in the structures of the pile driving rig , or a strain caused by the force effected by the torque on at least one point in the structures of the pile driving rig , or a deformation caused by the force effected by the torque on at least one point in the structures of the pile driving rig ; as well as by calculating the torque of the auger from a measurement result thus obtained, wherein the force to be measured for determining the torque is a supporting force between the frame of the driving motor of the auger rotator and the frame of the auger rotator, and said supporting force is measured by a force sensor placed in the lever arm placed between the frame of the driving motor of the auger rotator and the frame of the auger rotator . wherein the pile driving rig comprises an auger rotator including a frame of the auger rotator, a driving motor , a frame of the driving motor and a lever arm , wherein the method comprises determining the torque of the auger by measuring at least one of the following items in structures of the pile driving rig : a force effected by the torque on at least one point in the structures of the pile driving rig , or an elongation caused by the force effected by the torque on at least one point in the structures of the pile driving rig , or a strain caused by the force effected by the torque on at least one point in the structures of the pile driving rig , or a deformation caused by the force effected by the torque on at least one point in the structures of the pile driving rig ; as well as by calculating the torque of the auger from a measurement result thus obtained, wherein the force to be measured for determining the torque is a supporting force between the frame of the driving motor of the auger rotator and the frame of the auger rotator, and said supporting force is measured by a force sensor placed in the lever arm placed between the frame of the driving motor of the auger rotator and the frame of the auger rotator . a force effected by the torque on at least one point in the structures of the pile driving rig , or an elongation caused by the force effected by the torque on at least one point in the structures of the pile driving rig , or a strain caused by the force effected by the torque on at least one point in the structures of the pile driving rig , or a deformation caused by the force effected by the torque on at least one point in the structures of the pile driving rig ; as well as by calculating the torque of the auger from a measurement result thus obtained, wherein the force to be measured for determining the torque is a supporting force between the frame of the driving motor of the auger rotator and the frame of the auger rotator, and said supporting force is measured by a force sensor placed in the lever arm placed between the frame of the driving motor of the auger rotator and the frame of the auger rotator . <EOS>