A vehicle lighting unit comprising: a semiconductor laser light source configured to emit excitation light; a wavelength conversion material configured to receive excitation light emitted from the semiconductor laser light source and emit visible light by excitation; and a reflector having a reflecting surface configured to cover an upper side above the wavelength conversion material and reflect the light emitted from the wavelength conversion material so that the light can be diffused wider in a right-to-left direction than in a vertical direction on the basis of a posture where the lighting unit is mounted on a vehicle body, wherein the semiconductor laser light source includes a light emitting portion which has an elongated shape and which is configured to emit the excitation light that includes a linear polarization component along a longitudinal direction of the light emitting portion, the wavelength conversion material is disposed such that the excitation light emitted from the semiconductor laser light source can be incident thereon by an oblique incident angle, the part of the excitation light that is emitted from the semiconductor laser light source and regularly reflected off the surface of the wavelength conversion material can be incident on the reflecting surface of the reflector with an elongated area wider in the right-to-left direction than in a front-to-rear direction and form an illuminated portion (P BR) while being diffused wider in the right-to-left direction than in the vertical direction, the part of the excitation light that is emitted from the semiconductor laser light source and is incident on and converted by the wavelength conversion material to become visible light is reflected by the reflecting surface of the reflector forward so as to form a light distribution pattern wider in the right-to-left direction than in the vertical direction, the illuminated portion (P BR) of the part of excitation light regularly reflected off the surface of the wavelength conversion material is smaller in size than the light distribution pattern and is located within the light distribution pattern, characterized in that the excitation light emitted from the semiconductor laser light source and includes the linear polarization component along the longitudinal direction of the light emitting portion is incident on the wavelength conversion material by a Brewster's angle. a semiconductor laser light source configured to emit excitation light; a wavelength conversion material configured to receive excitation light emitted from the semiconductor laser light source and emit visible light by excitation; and a reflector having a reflecting surface configured to cover an upper side above the wavelength conversion material and reflect the light emitted from the wavelength conversion material so that the light can be diffused wider in a right-to-left direction than in a vertical direction on the basis of a posture where the lighting unit is mounted on a vehicle body, wherein the semiconductor laser light source includes a light emitting portion which has an elongated shape and which is configured to emit the excitation light that includes a linear polarization component along a longitudinal direction of the light emitting portion, the wavelength conversion material is disposed such that the excitation light emitted from the semiconductor laser light source can be incident thereon by an oblique incident angle, the part of the excitation light that is emitted from the semiconductor laser light source and regularly reflected off the surface of the wavelength conversion material can be incident on the reflecting surface of the reflector with an elongated area wider in the right-to-left direction than in a front-to-rear direction and form an illuminated portion (P BR) while being diffused wider in the right-to-left direction than in the vertical direction, the part of the excitation light that is emitted from the semiconductor laser light source and is incident on and converted by the wavelength conversion material to become visible light is reflected by the reflecting surface of the reflector forward so as to form a light distribution pattern wider in the right-to-left direction than in the vertical direction, the illuminated portion (P BR) of the part of excitation light regularly reflected off the surface of the wavelength conversion material is smaller in size than the light distribution pattern and is located within the light distribution pattern, characterized in that the excitation light emitted from the semiconductor laser light source and includes the linear polarization component along the longitudinal direction of the light emitting portion is incident on the wavelength conversion material by a Brewster's angle.