A light guide plate comprises: an outgoing radiation plane; a bottom opposed to the outgoing radiation plane; and an incidence plane disposed between the outgoing radiation plane and the bottom; wherein projections or recesses are formed on the bottom along the progress direction of incident light at a regular interval, the projections or recesses have long-side and short-side faces, an projection area of the long-side face on the outgoing radiation plane is three times or more that of the short-side face on the outgoing radiation plane, the long-side face is a projection, the long-side face is placed on the incidence plane side in the case of projections, the long-side face is placed on a side opposed to the incidence plane in the case of recesses.