  We theoretically study effects of surface roughness on the magnetic response
of small unconventional superconductors by solving the Eilenberger equation for
the quassiclassical Green function and the Maxwell equation for the vector
potential simultaneously and self-consistently. The paramagnetic phase of
spin-singlet $d$-wave superconducting disks is drastically suppressed by the
surface roughness, whereas that of spin-triplet $p$-wave disks is robust even
in the presence of the roughness. Such difference derives from the orbital
symmetry of paramagnetic odd-frequency Cooper pairs appearing at the surface of
disks. The orbital part of the paramagnetic pairing correlation is $p$-wave
symmetry in the $d$-wave disks, whereas it is $s$-wave symmetry in the $p$-wave
ones. Calculating the free-energy, we also confirm that the paramagnetic state
is more stable than the normal state, which indicates a possibility of
detecting the paramagnetic effect in experiments. Indeed our results are
consistent with an experimental finding on high-$T_c$ thin films.
