To provide a light guide plate and a light emitting device with good light distribution characteristics as well as a light guiding method.

The light guide plate is equipped with an incident face for incidence of light, a diffusion face to diffuse the light, and a light outgoing face to emit the light, and the diffusion face includes a plurality of diffusing surface dots of truncated cone shape or of spherical cone shape. Or, the light guide plate is equipped with the incident face for incidence of light, the diffusion face to diffuse the light, and the outgoing face to emit the light, and the diffusion face includes a plurality of diffusing surface dots of cone shape, of truncated cone shape, or of spherical cone shape, and the basic angle of diffusing surface dots is in a range 45 degrees or more and 60 degrees or less.