A lighting device (15, 16) for a straddled vehicle, comprising: a housing; a single light emitting diode; and an outer lens attached to the housing, extending in a direction perpendicular to an optical axis of the light emitting diode, and having translucency or transparency; wherein the outer lens comprises: a first light transmitting portion overlapping the light emitting diode in an optical axis direction of the light emitting diode, and a second light transmitting portion disposed at or in a non-overlapping position with the light emitting diode in the optical axis direction, the first light transmitting portion and the second light transmitting portion are integrally formed, the second light transmitting portion is longer than the first light transmitting portion in the extending direction of the outer lens which is perpendicular to the optical axis of the light emitting diode, the first light transmitting portion comprises: a first inclined surface provided on an outer surface of the first light transmitting portion and inclined with respect to the optical axis of the light emitting diode, and a second inclined surface provided on the outer surface of the first light transmitting portion and inclined with respect to the optical axis of the light emitting diode, the first inclined surface letting the light from the light emitting diode guided in the first light transmitting portion pass through and irradiating it toward the outside of the outer lens and reflecting a part of the light for irradiation toward the outside of the outer lens, an inclination angle of the second inclined surface with respect to the optical axis is larger than an inclination angle of the first inclined surface with respect to the optical axis, and the second inclined surface letting the light from the light emitting diode guided in the first light transmitting portion pass through and irradiating it toward the outside of the outer lens and reflecting a part of the light for irradiation toward the second light transmitting portion, and wherein in a cross section containing both the optical axis and the extending direction of the outer lens which is perpendicular to the optical axis, the first and second inclined surfaces are inclined so as to be away from each other toward the light emitting diode along the optical axis, and wherein in this cross section, both the first and second inclined surfaces are straight lines. a housing; a single light emitting diode; and an outer lens attached to the housing, extending in a direction perpendicular to an optical axis of the light emitting diode, and having translucency or transparency; wherein the outer lens comprises: a first light transmitting portion overlapping the light emitting diode in an optical axis direction of the light emitting diode, and a second light transmitting portion disposed at or in a non-overlapping position with the light emitting diode in the optical axis direction, a first light transmitting portion overlapping the light emitting diode in an optical axis direction of the light emitting diode, and a second light transmitting portion disposed at or in a non-overlapping position with the light emitting diode in the optical axis direction, the first light transmitting portion and the second light transmitting portion are integrally formed, the second light transmitting portion is longer than the first light transmitting portion in the extending direction of the outer lens which is perpendicular to the optical axis of the light emitting diode, the first light transmitting portion comprises: a first inclined surface provided on an outer surface of the first light transmitting portion and inclined with respect to the optical axis of the light emitting diode, and a second inclined surface provided on the outer surface of the first light transmitting portion and inclined with respect to the optical axis of the light emitting diode, a first inclined surface provided on an outer surface of the first light transmitting portion and inclined with respect to the optical axis of the light emitting diode, and a second inclined surface provided on the outer surface of the first light transmitting portion and inclined with respect to the optical axis of the light emitting diode, the first inclined surface letting the light from the light emitting diode guided in the first light transmitting portion pass through and irradiating it toward the outside of the outer lens and reflecting a part of the light for irradiation toward the outside of the outer lens, an inclination angle of the second inclined surface with respect to the optical axis is larger than an inclination angle of the first inclined surface with respect to the optical axis, and the second inclined surface letting the light from the light emitting diode guided in the first light transmitting portion pass through and irradiating it toward the outside of the outer lens and reflecting a part of the light for irradiation toward the second light transmitting portion, and wherein in a cross section containing both the optical axis and the extending direction of the outer lens which is perpendicular to the optical axis, the first and second inclined surfaces are inclined so as to be away from each other toward the light emitting diode along the optical axis, and wherein in this cross section, both the first and second inclined surfaces are straight lines.