Light guide device and display device

A light guide device comprising:

• a transparent light guide section configured to lead light inputted through a first end portion to an output section, the transparent light guide section including:
• a first plane extending from the first end portion toward a second end portion in a first direction;
• a second plane located on one side of the first plane in a second direction intersecting the first direction, the second plane extending parallel to the first plane in the first direction;
• and
• a plurality of partial reflection planes aligned in the first direction between the first plane and the second plane, the plurality of partial reflection planes being inclined at a same angle toward the first end portion with respect to a normal direction of the second plane, and the plurality of partial reflection planes having a plurality of pitches between adjacent partial reflection planes of the plurality of partial reflection planes that widen in the first direction from a side of the first end portion toward a side of the second end portion.