We consider the force acting on a spinning charged test particle (probe particle) with mass m and charge q in a slowly rotating Kerr-Newman-de Sitter (KNdS) black hole with mass M and charge Q . We consider the case in which the spin vector of the probe particle is parallel to the angular momentum vector of the KNdS spacetime. We take account of the gravitational spin-spin interaction under the slow rotation limit of the KNdS spacetime. When Q = M and q = m , we show that the force balance holds including the spin-spin interaction and the motion is approximately the same as that of a particle in de Sitter spacetime. This force cancellation suggests the possibility of the existence of an exact solution of a spinning multi-KNdS black hole.