A diffusing unit includes: a polarizing plate; and a diffusing layer integrally provided on a surface of the polarizing plate without an air layer therebetween. By using a display apparatus employing a collimating light guide plate and the diffusing unit, the optical performances such as resolution and viewing angle can be improved. Also, because gray scale inversion and color shifts can be reduced or eliminated using collimated light, image quality of the display apparatus can be improved.