A projection display is capable of suppressing both the trapezoidal distortion of an enlarged image projected on a screen by oblique projection and aberrations resulting from oblique projection and includes a projection optical system provided with lenses that can be easily manufactured and assembled. The projection optical system for obliquely projecting an image formed by a display device on the screen includes a free curved lens having a rotationally asymmetric free curved surface. The free curved lens has fringing parts having outlines of a shape coinciding with an arc of a circle having the center on the optical axis of the free curved lens.