A head-up display comprising: a display device having a display surface for displaying an image; and a projection optical system for projecting an image displayed on the display surface onto a viewing area for an observer, wherein the projection optical system includes a first reflective element and a second reflective element in order along an optical path from the display surface to the viewing area, wherein a reflective surface (121a, 122a) of at least one of the first reflective element and the second reflective element has a concave shape, a light beam that is emitted from a center of the display surface and reaches a center of the viewing area is referred to as a reference light beam (Lc), an intersection of the reference light beam (Lc) with the reflective surface of the first reflective element is referred to as a reference intersection point, a plane including the reference light beam (Lc) incident on the first reflective element and the reference light beam (Lc) reflected by the first reflective element is referred to as a reference plane, an intersection line of the reflective surface of the first reflective element with the reference plane is referred to as a reference intersection line (Bc), a tangent plane of the reflective surface of the first reflective element at the reference intersection point is referred to as a reference tangent plane, respective heights from two points, a vertically upper point and a vertically lower point, which are equidistant from the reference intersection point on the reference tangent plane, to the reflective surface of the first reflective element are referred to as a sag, and when perpendiculars (121u, 121l) extending from the two points, the vertically upper point and the vertically lower point, and normal to the reference tangent plane intersect with the reference intersection line (Bc), a sag at the vertically upper point is greater than a sag at the vertically lower point. a display device having a display surface for displaying an image; and a projection optical system for projecting an image displayed on the display surface onto a viewing area for an observer, wherein the projection optical system includes a first reflective element and a second reflective element in order along an optical path from the display surface to the viewing area, wherein a reflective surface (121a, 122a) of at least one of the first reflective element and the second reflective element has a concave shape, a light beam that is emitted from a center of the display surface and reaches a center of the viewing area is referred to as a reference light beam (Lc), an intersection of the reference light beam (Lc) with the reflective surface of the first reflective element is referred to as a reference intersection point, a plane including the reference light beam (Lc) incident on the first reflective element and the reference light beam (Lc) reflected by the first reflective element is referred to as a reference plane, an intersection line of the reflective surface of the first reflective element with the reference plane is referred to as a reference intersection line (Bc), a tangent plane of the reflective surface of the first reflective element at the reference intersection point is referred to as a reference tangent plane, respective heights from two points, a vertically upper point and a vertically lower point, which are equidistant from the reference intersection point on the reference tangent plane, to the reflective surface of the first reflective element are referred to as a sag, and when perpendiculars (121u, 121l) extending from the two points, the vertically upper point and the vertically lower point, and normal to the reference tangent plane intersect with the reference intersection line (Bc), a sag at the vertically upper point is greater than a sag at the vertically lower point.