Exciton spectra of CuAl_{1 - X}Ga_XSe₂ solid solutions are investigated by wavelength modulated optical reflectivity at low temperatures (10K). The energy position of n = 1 and 2 lines of the Γ₄(A), Γ₅(B) and Γ₅(C) exciton series, as well as the Γ₇(V₁)- Γ₆(C₁), Γ₆(V₂)- Γ₆(C₁), Γ₇(V₃)- Γ₆(C₁) energy intervals, and the crystal field and spin-orbit splitting of the valence band are determined. The effective electron mass (m_C1*) and hole masses (m_{V 1}*, m _{V 2}*, m_{V 3}*) are estimated for CuAl _{1 - X}Ga_XSe₂ solid solutions as a function of the X value.