To provide an illumination device which has high brightness, is especially high in front brightness and high in light utilization efficiency, in which it is easy to respond to increase in the size of the device, in which brightness unevenness in a front direction is eliminated without precise positioning between a light source and the other members, and which is superior in damage resistance and advantageous in productivity and thinning, and an image display device using this.

The problems are solved by using a member equipped with a light beam direction controlling means having minute unevenness of which a center line average roughness Ra is 0.05Ra0.5 m and of which a ten-point average roughness Rz is 0.5Rz5.0 m at the rear face of a face wherein a plurality of ridge-like convex parts are formed.