CuInSe2 (CIS) films with Cu/In ratios (γ) ranging from 0.81 to 1.81 have been grown by molecular beam epitaxy on (001)-oriented GaAs substrates at a substrate temperature of Ts=450°C. It is found that Cu-rich films tend to become Se-poor, and In-rich films tend to become Se-rich. X-ray diffraction patterns obtained from these films have shown the peaks with respect to CIS {n00} planes, clearly indicating epitaxial growth. Optical properties of the CIS films have been characterized by means of photoluminescence (PL) spectroscopy at 2 K. Many distinct emission lines including a band edge emission were present on PL spectra obtained from Cu-rich films. A broad emission (λ∼1.45 µm) appeared at γ=1.04, then became dominant with further decreasing γ.