An optical member includes a light guide. An inclination angle of a first reflecting surface of the light guide with respect to a first direction perpendicular to a normal direction of the first reflecting surface is defined as γr in a rotational direction about an axis extending in the normal direction. A line segment is defined by connecting the viewer and the light guide in a cross section perpendicular to the first direction. An inclination angle of the line segment with respect to a second direction perpendicular to the normal direction and the first direction is defined as β in a rotational direction about an axis extending in the first direction. The first reflecting surface is formed so as to satisfy Inequation of 10°≤arctan(tan γr×sin β)≤90°.