The CIGS film production method includes: a stacking step of stacking a layer (A) containing indium, gallium and selenium and a layer (B) containing copper and selenium, in this order in a solid phase over a substrate; and a heating step of heating the resulting stack of the layer (A) and the layer (B) to melt the layer (B) into a liquid phase, whereby copper is diffused from the layer (B) into the layer (A) to cause crystal growth; wherein the layer (A) is formed by repeatedly stacking a gallium selenide film (Y) and an indium selenide film (X) in this order and reducing a thickness ratio (Y/X) between the gallium selenide film (Y) and the indium selenide film (X) as the stacking is repeated.