A lamp unit includes at least one light source that emits light in a predetermined direction, and a light guide body including at least one incident surface where light emitted from the light source enters, a first emission surface that emits light entering from the incident surface in a horizontal direction, and a plurality of second emission surfaces that emits light entering the incident surface in a horizontal direction and emits light entering the incident surface to the upper side of the horizontal direction. The second emission surfaces are formed above the first emission surface at different positions in an up-down direction, and are positioned on the back side of the first emission surface so as to be spaced apart from one another in the horizontal direction.