According to one embodiment of the present invention, a composite film comprising an indication area for preventing forgery is provided. The indication area comprises a magnetic solution distributed in a cured medium. The magnetic solution is a colloidal solution in which a plurality of magnetic particles charged in the same polarity are dispersed in a fluid, at least one of reflective light and transmittance of the magnetic solution changing when a magnetic field is applied, and an expressive material, of which a predetermined characteristic is expressed when specific energy is applied, is present separately from the magnetic solution in the cured medium.