The invention relates to a method and a device for continuous and automatic monitoring and alignment of a propeller shaft (A), mounted in a plurality of bearings, in a ship upon hull deformations during operation. The inventive method substantially involves: measuring a parameter indicating the state of stresses in the shaft (A); calculating, by means of a special computer program, how the bearings (L) (the offsets) should be changed in view of the measured parameter and the prescribed conditions; adjusting the respective offsets by the calculated change. The inventive device substantially consists of: measuring means (M) which monitor a parameter indicating the state of stresses in the shaft (A); a computer (D) which receives values from the measuring means (M) and calculates, by means of a special program, how the bearings (the offsets) should be changed; control means (S) which receive the offset changes from the computer (D); an actuator which is actuated by the control means (S) and adjusts the respective offsets by the calculated change.