The motion of a particle in a perturbed gravitational field of a point mass is considered. A constant force is taken as a perturbation. The L-matrix is selected in such a manner that in regular coordinates the separation of variables takes place. Integration of the equations of motion of the problem under consideration is carried out. The solutions are expressed in terms of elliptic functions. A qualitative investigation of the integrals of motion is made, and numerical examples are presented.