The present application relates to a method of applying particles, an optical film and a method of manufacturing an active liquid crystal device. In the method of applying particles of the present application, the particles can be uniformly applied on a base material and fixed while maintaining the shape of particles. The optical film of the present invention produced by the above method can have excellent particle dispersity. A method of manufacturing an active liquid crystal device using the above method can maintain a cell gap uniformly while simplifying the manufacturing process and preventing gravity defects.