According to the present invention, a Cu—Ga alloy sputtering target which is a sintered body has a composition with 29.5 atom % to 43.0 atom % of Ga and a balance of Cu and inevitable impurities. A Cu—Ga alloy crystal particle in the sintered body has a structure in which γ phase particles are dispersed in a γ1-phase crystal particle. A method for producing the sputtering target includes a step of performing normal pressure sintering by heating a molded body formed of a powder mixture of a pure Cu powder and a Cu—Ga alloy powder in a reducing atmosphere, and a step of cooling the obtained sintered body at a cooling rate of 0.1° C./min to 1.0° C./min, at a temperature having a range of 450° C. to 650° C.