A back sheet for a photovoltaic module includes a single substrate film and a layer C, the layer C contains an acrylic resin as a major component, the substrate film including a layer A and a layer B, wherein the layer A contains a polyester resin as a major component, contains a white pigment in an amount of 5.0% by mass to 25% by mass, has a thickness of 5 μm or more, and is disposed on another surface of the back sheet, and the layer B contains a polyester resin as a major component, contains a white pigment in an amount of 1.0% by mass to less than 5.0% by mass based on the total amount of the layer B, and has a thickness accounting for 70% or more of the total thickness of the back sheet. The layer C may be made of a composition of an acrylic resin having a reactive functional group, a protected isocyanate compound, and an unprotected isocyanate compound.