We report the discovery of a new ultra-faint globular cluster in the constellation of Ursa Minor, based on stellar photometry from the MegaCam imager at the Canada-France-Hawaii Telescope. We find that this cluster, Munoz 1, is located at a distance of 45 + or - 5 kpc and at a projected distance of only 45' from the center of the Ursa Minor dwarf spheroidal galaxy. Using a maximum-likelihood technique we measure a half-light radius of 0'.5, or equivalently 7 pc, and an ellipticity consistent with being zero. We estimate its absolute magnitude to be M sub(V) = -0.4 + or - 0.9, which corresponds to L sub(V) = (ProQuest: Formulae and/or non-USASCII text omitted) L sub(middot in circle) and we measure a heliocentric radial velocity of -137 + or - 4 km s super(-1) based on Keck/DEIMOS spectroscopy. This new satellite is separate from Ursa Minor by ~30 kpc and 110 km s super(-1) suggesting the cluster is not obviously associated with the dSph, despite the very close angular separation. Based on its photometric properties and structural parameters we conclude that Munoz 1 is a new ultra-faint stellar cluster. Along with Segue 3 this is one of the faintest stellar clusters known to date.