  We report resistivity and magnetization of single crystal MgB2, focusing on
the broadening of superconducting (SC) transition in magnetic fields. In-plane
and out-of-plane resistivity indicate that the broadening of superconducting
transition is independent of Lorentz force and that it is merely dependent on
the magnetic field direction. In magnetization, diamagnetic signal begins to
appear at almost the same temperature as the onset temperature of resistivity
transition. These results suggest that the broadening is attributed not to the
surface superconductivity but to the superconducting fluctuation or the
vortex-liquid picture, owing to the short coherence length and the high
transition temperature of MgB2.
