Planar illumination device

A planar illumination device comprising:

• a plurality of light sources;
• a light guide plate that has a light-entering end surface, two main surfaces and an opposite end surface, a light emitted from each of the plurality of light sources entering the light-entering end surface, the two main surfaces intersecting with the light-entering end surface and facing each other, the opposite end surface facing the light-entering end surface and the light guide plate guiding the light toward the opposite end surface and emitting the light from a light-emission surface that is one of the two main surfaces;
• and
• a fixing member that is disposed in such a manner that covers at least an area in the light-entering end surface side of the light-emission surface of the light guide plate, wherein
• the light guide plate has a plurality of first prisms and a plurality of second prisms, the plurality of first prisms being formed on the light-emission surface of the light guide plate in such a manner that extends toward the opposite end surface in an area covered by the fixing member in the light-entering end surface side and the plurality of second prisms being formed on the light-emission surface of the light guide plate in such a manner that extends toward the opposite end surface in an area in the opposite end surface side with respect to the area covered by the fixing member in the light-entering end surface side,
• number of the plurality of second prisms per unit length in a width direction of the light guide plate is smaller than number of the plurality of first prisms per unit length in the width direction, and
• each of the plurality of second prisms is connected with any of the plurality of first prisms in a prism extending direction.