  We have performed 59Co NMR experiments on the ferromagnetic superconductor
UCoGe under magnetic fields (H) along the a- and b- axes to investigate the
relationship between ferromagnetic properties and superconductivity. The
ferromagnetic ordering temperature TCurie is suppressed and the nuclear
spin-lattice relaxation rate 1/T1 at 2 K is enhanced in H || b, although TCurie
and 1/T1 are unchanged in H || a, indicating that the ferromagnetic criticality
is induced only when H is applied along the b axis. We show the close
relationship between the magnetic anisotropies and the superconducting ones
reported by Aoki et al.: the superconductivity is gradually suppressed in H ||
a, but enhanced in H || b above 5 T. We strongly suggest that the enhancement
of the superconductivity observed in H || b originates from the field induced
ferromagnetic criticality, as pointed out by Aoki et al and Mineev.
