Compound solar battery

A compound solar battery in which

• a surface electrode, a laminated film, a substrate, and a back electrode are stacked in order, wherein there is a part of a surface of the laminated film not contacted by the surface electrode, wherein:
• the laminated film comprises:
• a reflection layer formed of an AlGaAs layer, wherein the reflection layer comprises a front surface-side reflection layer and a back surface-side reflection layer;
• a front surface-side light absorption layer formed between the surface electrode and the reflection layer;
• and
• a back surface-side light absorption layer formed between the reflection layer and the substrate;
• and wherein
• an Al content ratio in the front surface-side reflection layer is greater than that in the back surface-side reflection layer, and
• the back surface-side light absorption layer comprises:
• a first InGaP layer, a first GaAs layer, a second InGaP layer, a second GaAs layer, and a third InGaP layer formed by laminating from a side of the substrate, and wherein:
• a film thickness of the second GaAs layer is larger than that of the first GaAs layer.