We report the new detection of ^7^BeII in the ultraviolet spectra of V5669 Sgr during its early decline phase (+24 and +28d). We identified three blueshifted absorption systems in our spectra. The first two, referred to as low- and high-velocity components, were noticeably identified among HI Balmer, NaI D, and FeII whose lower energies of transients are low (<4eV). The third absorption component was identified among NII, HeI, and CII lines whose lower energy levels are relatively high (9-21eV). The absorption lines of ^7^BeII at 3130.583{AA} and 3132.228{AA} were identified as the first and second components in our observations. No evidence suggested the existence of LiI at 6708{AA} in any velocity components. The estimated number density ratio of lithium relative to hydrogen, which was finally produced by this object using the equivalent widths of ^7^Be and CaII K, N(^7^Li)/N(H)_final_, is 4.0+/-0.7x10^-6^. This value is an order of magnitude lower than the average observed values for classical novae wherein 7Be has been detected, and is comparable to the most optimistic value of theoretical predictions.