A Cu—Ga alloy sintered-compact sputtering target having a Ga concentration of 40 to 50 at % and Cu as the balance, wherein the sintered-compact sputtering target is characterized in that the relative density is 80% or higher, and the compositional deviation of the Ga concentration is within ±0.5 at % of the intended composition. A method of producing a Cu—Ga alloy sintered-compact sputtering target having a Ga concentration of 40 to 50 at % and Cu as the balance, wherein the method thereof is characterized in that Cu and Ga raw materials are melted and cooled/pulverized to produce a Cu—Ga alloy raw material powder, and the obtained material powder is further hot-pressed with a retention temperature being between the melting point of the mixed raw material powder and a temperature 15° C. lower than the melting point and with a pressure of 400 kgf/cm2 or more applied to the sintered mixed raw material powder. Provided are a sputtering target having very low compositional deviation and high density; a method of producing the target; a light-absorbing layer having a Cu—Ga based alloy film; and a CIGS solar cell including the light-absorbing layer.