  We study the new binary intermetallic superconductor MgB2 using
high-resolution photo-emission spectroscopy. The superconducting-state spectrum
measured at 5.4 K shows a coherent peak with a shoulder structure, in sharp
contrast to that expected from a simple isotropic-gap opening. The spectrum can
be well reproduced using the weighted sum of two Dynes functions with the gap
sizes of 1.7 and 5.6 meV. Temperature-dependent study shows that both gaps
close at the bulk transition temperature. These results provide spectroscopic
evidence for a multiple gap of MgB2.
