  We report the discovery of superconductivity on the border of long-range
magnetic order in the itinerant-electron helimagnet MnP via the application of
high pressure. Superconductivity with Tsc~1 K emerges and exists merely near
the critical pressure Pc~8 GPa, where the long-range magnetic order just
vanishes. The present finding makes MnP the first Mn-based superconductor. The
close proximity of superconductivity to a magnetic instability suggests an
unconventional pairing mechanism. Moreover, the detailed analysis of the
normal-state transport properties evidenced non-Fermi-liquid behavior and the
dramatic enhancement of the quasi-particle effective mass near Pc associated
with the magnetic quantum fluctuations.
