A planar illumination device includes at least one light source, a housing structure, at least one light guide plate, and at least one light exiting surface. The at least one light source is received in the housing structure. The housing structure includes at least one light emitting surface through which the light emitted from the at least one light source exits the at least one housing. The at least one light guide plate includes at least one light incidence surface through which the light enters into the at least one light guide plate, and contacts with the at least one light emitting surface. The light exits the at least one light guide plate through the at least one light exiting surface. The at least one light exiting surface includes a plurality of continuously connected bulge points formed thereon.