A laser light source device (1, 2, 3, 4) comprising: a laser light source for emitting laser light from a laser emission aperture thereof; a condenser lens disposed in front of said laser light source in a laser emission direction to collect said laser light, or a wavelength converter disposed in front of said laser light source in a laser emission direction to receive said laser light and to emit light of a different wavelength from that of said laser light; and a light guide for covering said laser emission aperture so as to guide said laser light, said light guide having a reflective surface extending from said laser light source to said condenser lens or to said wavelength converter such that said reflective surface extends along an optical axis of said laser light, wherein said light guide has a second surface which is located opposite to said reflective surface with respect to said optical axis of said laser light, said second surface having one of (i) an antireflective property, and (ii) a sufficient separation distance from the optical axis of said laser light so as not to reflect said laser light, wherein said reflective surface extends in a direction parallel to the optical axis of said laser light. wherein said laser light source includes a laser diode having an pn joint surface, and said reflective surface is oriented in a direction orthogonal to the pn joint surface of the laser diode; wherein the beam spot of said laser light emitted by said laser light source has oval shape, the width of said beam spot in direction parallel to said pn joint surface of said laser diode being smaller than the width of said beam spot in direction vertical to said pn joint surface of said laser diode, the light intensity distribution of said beam spot being a symmetric Gaussian distribution, and wherein said laser light source device satisfies the following inequality: W < 0.064θ H - 0.032 where θ H is a full width at half maximum angle in degrees of said laser light in a direction parallel to the pn joint surface of said laser diode, and W is a distance in millimeters between an optical axis center of said laser light and said reflective surface. a laser light source for emitting laser light from a laser emission aperture thereof; a condenser lens disposed in front of said laser light source in a laser emission direction to collect said laser light, or a wavelength converter disposed in front of said laser light source in a laser emission direction to receive said laser light and to emit light of a different wavelength from that of said laser light; and a light guide for covering said laser emission aperture so as to guide said laser light, said light guide having a reflective surface extending from said laser light source to said condenser lens or to said wavelength converter such that said reflective surface extends along an optical axis of said laser light, wherein said light guide has a second surface which is located opposite to said reflective surface with respect to said optical axis of said laser light, said second surface having one of (i) an antireflective property, and (ii) a sufficient separation distance from the optical axis of said laser light so as not to reflect said laser light, wherein said reflective surface extends in a direction parallel to the optical axis of said laser light. wherein said laser light source includes a laser diode having an pn joint surface, and said reflective surface is oriented in a direction orthogonal to the pn joint surface of the laser diode; wherein the beam spot of said laser light emitted by said laser light source has oval shape, the width of said beam spot in direction parallel to said pn joint surface of said laser diode being smaller than the width of said beam spot in direction vertical to said pn joint surface of said laser diode, the light intensity distribution of said beam spot being a symmetric Gaussian distribution, and wherein said laser light source device satisfies the following inequality: W < 0.064θ H - 0.032 where θ H is a full width at half maximum angle in degrees of said laser light in a direction parallel to the pn joint surface of said laser diode, and W is a distance in millimeters between an optical axis center of said laser light and said reflective surface.