A light source device including a light guide plate and a light source, in which the light guide plate includes an incident surface on which light emitted from the light source is incident, an emission surface emitting light incident from the incident surface, and a propagating reflection surface which is a surface opposite to the emission surface and which propagates and reflects the light incident from the incident surface toward the emission surface, the propagating reflection surface has approximately V-shaped grooves and the V-shaped grooves have two kinds of grooves.