The present invention provides a
foreign object inspection device that can accurately determine whether a
foreign object is attached to the front or back surface of a material. [Solution] The device comprises a
laser light irradiation unit that irradiates a light-transmitting film by scanning a
laser beam linearly from one side of the film; a
scattered light detection unit that detects a first
scattered light intensity, which is the intensity of
scattered light generated from
foreign matter adhering to the film due to the P-polarization component of the
laser light, and a second scattered
light intensity, which is the intensity of scattered light generated from
foreign matter adhering to the film due to the S-polarization component of the
laser light; and a determination unit that determines whether the
foreign matter adhering to the film is attached to one side or the other side, based on the first and second scattered light intensities detected by the scattered
light detection unit. The device is configured such that, when the intersection of a
scanning plane, which is the same plane as the region through which the scanned
laser light passes, and an incident plane, which is a plane perpendicular to the scanning line of the
laser light on the film, is taken as a
reference line, the scattered
light detection unit is positioned on a plane that intersects the incident plane with the
reference line at an angle of 40 degrees or more and 50 degrees or less.