To appropriately configure a solar system that has a large light receiving area, by providing a Fresnel lens for a solar system with a structure that is less likely to bend by its weight.

Many prism portions 11 and 12 are arranged along a reference surface 10 extending obliquely relative to an optical axis A, and thereby exhibit the action of one lens as a whole. The many prism portions 11 and 12 form steps, each of the prisms 11 and 12 includes an incident face 2 which sunlight traveling parallel to the optical axis A enters, and a prism face projecting on the incidence side. The prism face has a first face 3 away from the optical axis A, and a second face 4 close to the optical axis A.