  In-medium modification of the eta' mass is discussed in the context of
partial restoration of chiral symmetry in nuclear medium. We emphasize that the
U_A(1) anomaly effects causes the eta'-eta mass difference necessarily through
the chiral symmetry breaking. As a consequence, the eta' mass is expected to be
reduced by order of 100 MeV in nuclear matter where about 30% reduction of
chiral symmetry takes place. The strong attraction relating to the eta' mass
generation eventually implies that there should be also a strong attractive
interaction in the scalar channel of the eta'-N two-body system. We find that
the attraction can be strong enough to form a bound state.
