A projection display system comprising: a reflection display device having a plurality of pixels arranged in a matrix and adapted to project forward an image beam by controlling reflected light that has entered from a front surface of the reflection display device by the plurality of pixels so arranged; a light source system optical member for projecting an illumination beam toward the reflection display device from a direction inclined in one direction relative to the front surface direction of the reflection display device; a projection system optical member which is constituted by a plurality of lenses for projecting an image beam that has exited from the reflection display device on a projection surface; a relay lens disposed in such a manner that one surface thereof faces the reflection display device and the other surface thereof faces the light source optical member and the projection optical system member, an inner circumferential surface of the projection system optical member has a light absorbing characteristics characterized in that the plurality of lenses which constitute the projection system optical member are disposed in the interior of a lens barrel composed of subdivided lens barrels -, and the one surface of the relay lens, which faces the light source optical member and the projection optical system member, is formed into a surface having a concave or plane curvature which allows a part of the beam which has been surface reflected on the one surface to exit in a direction in which the part of the beam does not enter at least the effective area of the lens of the plurality of lenses which is disposed nearest the exit end of the projection system optical member and is absorbed by the light-absorbing inner circumferential surface of the projection system optical member, and the other surface of the relay lens, which faces the reflection display device, is formed into a surface having a convex curvature, which allows the illumination beam that has entered from the one surface which faces the light source system optical member and the projection system optical member to be corrected into a substantially parallel beam which follows a direction inclined at a predetermined angle relative to the front surface direction of the reflection display device so as to make the parallel beam so corrected enter the reflection display device, and which allows an image beam that has exited from the reflection display device enter the projection system optical member, in association with the curvature of the one surface of the relay lens which faces the light source optical member and the projection optical system member. a reflection display device having a plurality of pixels arranged in a matrix and adapted to project forward an image beam by controlling reflected light that has entered from a front surface of the reflection display device by the plurality of pixels so arranged; a light source system optical member for projecting an illumination beam toward the reflection display device from a direction inclined in one direction relative to the front surface direction of the reflection display device; a projection system optical member which is constituted by a plurality of lenses for projecting an image beam that has exited from the reflection display device on a projection surface; a relay lens disposed in such a manner that one surface thereof faces the reflection display device and the other surface thereof faces the light source optical member and the projection optical system member, an inner circumferential surface of the projection system optical member has a light absorbing characteristics characterized in that the plurality of lenses which constitute the projection system optical member are disposed in the interior of a lens barrel composed of subdivided lens barrels -, and the one surface of the relay lens, which faces the light source optical member and the projection optical system member, is formed into a surface having a concave or plane curvature which allows a part of the beam which has been surface reflected on the one surface to exit in a direction in which the part of the beam does not enter at least the effective area of the lens of the plurality of lenses which is disposed nearest the exit end of the projection system optical member and is absorbed by the light-absorbing inner circumferential surface of the projection system optical member, and the other surface of the relay lens, which faces the reflection display device, is formed into a surface having a convex curvature, which allows the illumination beam that has entered from the one surface which faces the light source system optical member and the projection system optical member to be corrected into a substantially parallel beam which follows a direction inclined at a predetermined angle relative to the front surface direction of the reflection display device so as to make the parallel beam so corrected enter the reflection display device, and which allows an image beam that has exited from the reflection display device enter the projection system optical member, in association with the curvature of the one surface of the relay lens which faces the light source optical member and the projection optical system member.