A document photosensor is provided which comprises a substrate 11, 12, a bracket 41, 42 disposed on substrate 11, 12 for forming a light diffusion chamber 53 and a light receiving chamber 58 separated from each other, an LED chip 21, 31 surface-mounted on substrate 11, 12 in light diffusion chamber 53, and a PD chip 37, 38 surface-mounted on substrate 11, 12 in light receiving chamber 58. These chips 21, 37, 31 and 38 are secured at precise locations on a substrate 11 and 12 with accuracy on the order of a few micrometers or less to exactly detect by PD chip 37, 38 a light irradiated from LED chip 21 or 31 after reflection of the light on a bill 50 moved along a passageway 55 to improve validation performance of bill 50.