Orifice, liquid feeding device and coating device using the same, and method of manufacturing optical film

Provided is an orifice which promotes deaggregation and prevents particles from staying in one place. Also, provided are a liquid feeding device using the same, an application device, and a method for producing an optical film. To this end, the orifice comprises: an orifice main body; an inlet positioned at an entrance of the orifice main body; a shaft diameter part including a curved surface of which the radius of curvature connected to the inlet is 1-10 mm, and further including a primary inner lateral wall having a shaft diameter surface connected to the curved surface and axially crossing a narrow aperture at an angle of 120-180; and an enlarged diameter part connected to an outlet from the narrow aperture and including a secondary inner lateral wall enlarged at an angle of 2-10. The ratio of the diameter of the inlet to the diameter of the narrow aperture is 0.07-0.18.