A package inspection system is provided, where an electromagnetic-wave detection part is hardly affected by illumination light for optical detection. Below a gap 6c of a conveyor mechanism 6 for conveying a package, provided are an X-ray sensor 13 for detecting X rays transmitted through the package and an illumination part 16 for applying illumination light to the gap 6c. The X-ray sensor 13 and the illumination part 16 are separated from each other by a partition 42. A light-shielding member 43 is placed in the path of X-ray incidence to the X-ray sensor 13. The light-shielding member 43 is formed of a material that allows passage of the X rays but does not allow passage of the illumination light and is hardly deteriorated by irradiation of the X rays, e.g., a carbon sheet.