Abstract: The present invention relates to a prism diffuser for diffracting and spreading light, and in particular to a prism diffuser for diffracting and spreading light which is capable of spreading light in a certain direction at a wider angle based on a structure combined with a prism capable of diffracting light on a surface of a medium formed of a glass which transmits or reflect light, a film formed of a transparent synthetic resin material or a metallic plate and a diffuser capable of spreading light and diffracting, spreading and transmitting light into two directions or diffracting, spreading and reflecting light in one direction.