Reflective plate for solar thermal power generation

A reflective plate for solar thermal power generation is provided with a glass layer, a mirror surface layer, a mirror surface protection layer, an adhesive layer, and a composite layer in this order from the sunlight entry side. The composite layer comprises a resin substrate having a thickness of 100-500 µm and at least one weather-resistant layer in this order from the side of said composite layer that is closer to the mirror surface layer.