A head-up display includes an illuminating device and an optical reflection unit for reflecting light from the illuminating device. The illuminating device includes a plurality of light sources arranged in a first direction and a plurality of first lenses disposed corresponding to the light sources in an emitting direction of the light sources. Each of the first lenses has a first incidence plane and a first emitting plane. At least one of the first incidence plane and the first emitting plane is convex. The illuminating device also includes a second lens disposed in an emitting direction of the plurality of first lenses and a diffusing plate disposed in an emitting direction of the second lens. The second lens has a second incidence plane and a second emitting plane. At least one of the second incidence plane and the second emitting plane has a concave cross-section in the first direction.