The configuration of force-free magnetic field in the 'star-disk' system is considered in the paper. It is suggested that the star is rotating and the disk is at rest. The footpoints of magnetic field lines are frozen into the star and the disk. In this paper the current layer formation takes place on the disk, not in the corona. The magnetic field lines are deformed and extended to infinity. The field energy increases without limit. The angular momentum of the disk is lost due to the tension of the magnetic field lines. The main results have been obtained through the numerical solution of boundary value problem for nonlinear differential equations. The solution nonunity is main feature of the problem.

Mathematical modelling in actual problems of science and technics