Solar cell back sheet and solar cell module

Provided are: a solar cell sealing sheet exhibiting excellent adhesion with respect to a sealant, storage stability, productivity, and environment resistance; and a solar cell module in which the solar cell sealing sheet is used. The present invention is a solar cell back sheet having a single substrate film and a layer C. The layer C has an acrylic resin as the main component. The substrate film has a layer A and a layer B. Layer A has a polyester resin as the main component, contains 5.0-25% by mass of a white pigment, has a thickness of 5 μm or greater, and is disposed on the outermost surface on the other side of a back sheet. Layer B has a polyester resin as the main component, contains 1.0% by mass to less than 5.0% by mass of a white pigment in relation to all components of layer B, and has a thickness representing 70% or more of the entire back sheet. Another invention is a solar cell back sheet in which layer C is obtained from a composition of an acrylic resin having a reactive functional group, a protected isocyanate compound, and an unprotected isocyanate compound.