An image reader A1 according to the present invention comprises a pair of light source devices 3, a light guide member 4, a first and a second reflectors 7A and 7B, a plurality of light receiving elements 5, and a case 1. The image reader A1 further includes a first fitting contrivance 71 for positioning the first reflector 7A relative to the case 1 by inserting the first reflector 7A into the case 1 in the insertion direction z, a second fitting contrivance 72 for positioning the light guide member 4 relative to the case 1 by inserting the light guide member 4 into the case 1 in the insertion direction z, and a third fitting contrivance 73 for positioning the second reflector 7B relative to the case 1 by inserting the second reflector 7B into the case 1 in the insertion direction z.