A foreign substance inspection apparatus includes an irradiating unit and first and second detecting units. The irradiating unit is configured to emit irradiating light to be obliquely incident on a surface to be inspected to form a linear irradiation region on the surface to be inspected. The first and second detecting units are arranged on the same side as that provided with the irradiating unit with respect to the surface to be inspected, and they are configured to detect scattered light caused by a foreign substance on the surface to be inspected. The first and second detecting units are arranged at opposite positions with respect to a plane containing the linear irradiation region.