We observed ligand-sensitized and up-conversion photoluminescence (PL) in vacuum -deposited thin films of an infrared electroluminescent organic erbium complex, erbium (III) tris(8-hydroxyquinoline) (ErQ). The PL intensity at 1.55 mum was increased by three orders of magnitude by changing the photo-excited species from Er3+ to the organic ligand (Q). This strong enhancement was ascribable to ligand-sensitized PL based on the excited state energy transfer from Q to Er3+. We simultaneously detected up-conversion PL from Er3+ in the ultraviolet region. The up-conversion PL is emitted due to excited state absorption, which indicates that vacuum-deposited ErQ thin films are weak electron-phonon coupling systems.