PURPOSE: To couple the shaft of an established machine with the shaft of a machine easily and besides with accuracy on the spot.

CONSTITUTION: This coupling is provided with a middle plate 1, which is installed between the hydraulic turbine shaft flange 10a on drive side and the generator shaft flange 9a on driven side and has approximately the same thickness and size as the generator shaft flange 9a, a reamer stud 13 and a nut 14, which fasten both flanges 9a and 10a and the middle plate 1, and a bush 2, which is inserted in the space around the reamer stud 13 inserted into the reamer hole of the generator flange 9a. Hereby, the adjustment of the interval between shafts and the coupling on the site becomes easy, and the shafts can be coupled with accuracy.