  We explore how the internal structure of a test particle affects its
equatorial stable circular orbits around the Kerr black hole with or without a
cosmological constant. To this end, we first explicitly write equations of
motion for a test particle in the pole-dipole-quadrupole approximation
specifying the quadrupole momentum tensor to a spin-induced model. Then we
calculate characteristic quantities -- radius, angular momentum, energy,
angular velocity, and impact parameter -- for the particles on the stable
circular orbits. Once the pole-dipole-quadrupole approximation is taken, we
find that for a particle on an innermost stable circular orbit, all
characteristic quantities, except the angular velocity, become greater relative
to the pole-dipole case. In contrast, for a particle on an outermost stable
circular orbit, which only exists in the case of the spacetime background being
asymptotically de Sitter, it is the radius that becomes smaller while all other
quantities become greater.
