A back protective sheet for a solar cell module containing a polyester support that is biaxially stretched and then subjected to a thermal fixation treatment; and a polymer layer arranged to be in contact with at least one surface of the polyester support, wherein the polymer layer contains a binder having at least one functional group selected from a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, and a carbonyl group; a pigment; and a crosslinking agent-derived structure, and the polyester support contains a polyester, a pigment, and an terminal blocking agent, has excellent adhesion between the support and the functional layer after wet heat aging.