A line light source being used as a light source of an optical line sensor unit for reading a paper sheet, comprising: a light guide extending in a longitudinal direction and made of resin or optical glass which transmits a light in a wavelength range (a) from UV light to a visible light, or (b) from UV light through visible light to infrared light; a first light source portion disposed at a first end surface of the light guide to emit UV light; and a second light source portion disposed at a second end surface opposed to the first end surface of the light guide in the longitudinal direction to emit (a) visible light or (b) light in a wavelength range from visible light to infrared light; a first optical filter disposed between the first end surface of the light guide and the first light source portion, or covered to the first end surface of the light guide, transmitting the UV light emitted from the first light source portion, and reflecting or blocking (a) the visible light or (b) the light in the wavelength range from visible light to infrared light to prevent fluorescence emitted from the first light source portion from entering into the light guide; and a second optical filter disposed between the second end surface of the light guide and the second light source portion, or covered to the second end surface of the light guide, transmitting (a) the visible light or (b) the light in the wavelength range from visible light to infrared light emitted from the second light source portion, and reflecting or blocking UV light to prevent the UV light emitted from the first light source portion from illuminating the second light source portion through the second end surface of the light guide, and fluorescence secondarily emitted from the second light source portion from entering into the light guide, wherein the light emitted from the first light source portion, or the light emitted from the second light source portion is emitted from a light exit surface of the light guide. a light guide extending in a longitudinal direction and made of resin or optical glass which transmits a light in a wavelength range (a) from UV light to a visible light, or (b) from UV light through visible light to infrared light; a first light source portion disposed at a first end surface of the light guide to emit UV light; and a second light source portion disposed at a second end surface opposed to the first end surface of the light guide in the longitudinal direction to emit (a) visible light or (b) light in a wavelength range from visible light to infrared light; a first optical filter disposed between the first end surface of the light guide and the first light source portion, or covered to the first end surface of the light guide, transmitting the UV light emitted from the first light source portion, and reflecting or blocking (a) the visible light or (b) the light in the wavelength range from visible light to infrared light to prevent fluorescence emitted from the first light source portion from entering into the light guide; and a second optical filter disposed between the second end surface of the light guide and the second light source portion, or covered to the second end surface of the light guide, transmitting (a) the visible light or (b) the light in the wavelength range from visible light to infrared light emitted from the second light source portion, and reflecting or blocking UV light to prevent the UV light emitted from the first light source portion from illuminating the second light source portion through the second end surface of the light guide, and fluorescence secondarily emitted from the second light source portion from entering into the light guide, wherein the light emitted from the first light source portion, or the light emitted from the second light source portion is emitted from a light exit surface of the light guide.