Abstract: A defect detection method of a layered film having a polarizing plate and an optical compensation layer includes steps of: applying light from a light source arranged at the polarizing plate layer side of the film surface of the layered film; a step of imaging a transmitting light image of the layered film by an imaging unit arranged at the optical compensation layer side of the film surface; and a defect detection step for detecting a defect existing on the layered film according to the transmitting light image captured by the imaging unit. The imaging unit performs imaging via an inspection polarizing filter arranged on the optical path between the light source and the imaging unit and adjacent to the imaging unit; and an inspection phase difference filter arranged on the optical path between the light source and the imaging unit and between the inspection polarizing filter and the layered film.

Abstract: When inspecting a defect of a layered film having a polarizer by using an inspection polarizing filter or an inspection phase difference filter, members to be arranged in the imaging optical path are arranged in an appropriate order. A defect detection method of a layered film (11) having a polarizing plate (1) and an optical compensation layer includes: a step of applying light from a light source arranged at the polarizing plate layer side of the film surface of the layered film (11); a step of imaging a transmitting light image of the layered film (11) by an imaging unit (12) arranged at the optical compensation layer side of the film surface; and a defect detection step for detecting a defect existing on the layered film (11) according to the transmitting light image captured by the imaging unit (12).