Abstract: The invention relates to an endoprosthesis for a shoulder joint comprising a rotating piece which is connected to a shaft part such that it can rotate around a first axis, and comprising an axial directional piece which is connected to said rotating piece such that it can rotate around a second axis. Both pivotal axes are perpendicular to one another and the second axis is perpendicular to the axis of the directional piece. The spherical cap is either placed directly on the directional piece, or an eccentric ring or an oblong hole ring which supports the spherical cap is provided between the spherical cap and directional piece. Two or more eccentric rings can also be provided. The spherical cap can comprise a centric or eccentric conical surface. The direction of the first axis can be selected in a relatively free manner.