An information-reading element (10a, 10b, 20, 30) for reading information from an object (13a, 23a, 33a), the information-reading element comprising: a polarized light emitting part (11a, 21a, 31a) emitting linearly polarized light as outgoing light (15a,25a,35a), a polarized light receiving part (11b, 21b, 31b) receiving returned light, the polarized light emitting part (11a, 21a, 31a) and the polarized light receiving part (11b, 21b, 31b) respectively having different polarization characteristics, a polarization characteristic changing part (13b, 23b, 33b) changing the polarization characteristics of the outgoing light (15a, 25a, 35a) and light reflected from the object (13a, 23a, 33a) and being arranged at a position through which the outgoing light and the reflected light pass, wherein the polarization characteristic changing part (13b, 23b, 33b) gives rise to a change A in the polarization characteristic when the outgoing light (15a, 25a, 35a) passes therethrough and gives rise to a change B in the polarization characteristic when the reflected light passes therethrough to form the returned light so that the polarization characteristic of the returned light matches the polarization characteristic of the polarized light receiving part due to the change A and the change B, characterized in that: the polarized light emitting part (11a, 21a, 31a), the polarized light receiving part, the object (13a, 23a, 33a), and the polarization characteristic changing part (13b, 23b, 33b) are arranged at positions intersecting with a same optical axis, the polarized light receiving part (11b, 21b, 31b) is provided on an opposite side of the object (13a, 23a, 33a) with the polarized light emitting part (11a, 21a, 31a) interposed between the polarized light receiving part (11b, 21b, 31b) and the object (13a, 23a, 33a), the polarized light emitting part (11a, 21a, 31a) has a light transmission characteristic which passes polarized light having a polarizing direction that differs by 90° from emitted linearly polarized light, and in that the parts of the information-reading element are arranged so that the returned light is transmitted through the polarized light emitting part (11a, 21a, 31a) to reach the polarized light receiving part (11b, 21b, 31b). a polarized light emitting part (11a, 21a, 31a) emitting linearly polarized light as outgoing light (15a,25a,35a), a polarized light receiving part (11b, 21b, 31b) receiving returned light, the polarized light emitting part (11a, 21a, 31a) and the polarized light receiving part (11b, 21b, 31b) respectively having different polarization characteristics, a polarization characteristic changing part (13b, 23b, 33b) changing the polarization characteristics of the outgoing light (15a, 25a, 35a) and light reflected from the object (13a, 23a, 33a) and being arranged at a position through which the outgoing light and the reflected light pass, wherein the polarization characteristic changing part (13b, 23b, 33b) gives rise to a change A in the polarization characteristic when the outgoing light (15a, 25a, 35a) passes therethrough and gives rise to a change B in the polarization characteristic when the reflected light passes therethrough to form the returned light so that the polarization characteristic of the returned light matches the polarization characteristic of the polarized light receiving part due to the change A and the change B, characterized in that: the polarized light emitting part (11a, 21a, 31a), the polarized light receiving part, the object (13a, 23a, 33a), and the polarization characteristic changing part (13b, 23b, 33b) are arranged at positions intersecting with a same optical axis, the polarized light receiving part (11b, 21b, 31b) is provided on an opposite side of the object (13a, 23a, 33a) with the polarized light emitting part (11a, 21a, 31a) interposed between the polarized light receiving part (11b, 21b, 31b) and the object (13a, 23a, 33a), the polarized light emitting part (11a, 21a, 31a) has a light transmission characteristic which passes polarized light having a polarizing direction that differs by 90° from emitted linearly polarized light, and in that the parts of the information-reading element are arranged so that the returned light is transmitted through the polarized light emitting part (11a, 21a, 31a) to reach the polarized light receiving part (11b, 21b, 31b). the polarized light emitting part (11a, 21a, 31a), the polarized light receiving part, the object (13a, 23a, 33a), and the polarization characteristic changing part (13b, 23b, 33b) are arranged at positions intersecting with a same optical axis, the polarized light receiving part (11b, 21b, 31b) is provided on an opposite side of the object (13a, 23a, 33a) with the polarized light emitting part (11a, 21a, 31a) interposed between the polarized light receiving part (11b, 21b, 31b) and the object (13a, 23a, 33a), the polarized light emitting part (11a, 21a, 31a) has a light transmission characteristic which passes polarized light having a polarizing direction that differs by 90° from emitted linearly polarized light, and in that the parts of the information-reading element are arranged so that the returned light is transmitted through the polarized light emitting part (11a, 21a, 31a) to reach the polarized light receiving part (11b, 21b, 31b).