The field of attraction of a rigid body is studied. It is assumed, that the body is close to dynamically symmetric one. The problem of approximation of body’s field of attraction by the field of attraction of three homogeneous balls is considered. The goal of such approximation is to provide coincidence of the terms up to the fifth order of smallness in the series expansions for gravitational potentials of the body and three balls. As an example, the approximation of asteroid (433) Eros by three balls is considered.