To provide an optical film wherein deterioration of a diimonium compound in an adhesive layer is prevented, and a process for its production. An optical film comprising a base film and an adhesive layer which is formed on the base film and has a massive material dispersed in an adhesive, wherein the massive material contains a diimonium compound represented by the following formula (1) and has a melting point of at least 200° C.: wherein R1 to R8 represent each independently an unsubstituted or substituted, same or different, C1-6 aliphatic hydrocarbon group, provided that from 4.9 to 8 groups among R1 to R8 are a C1-3 aliphatic hydrocarbon group (in which some of hydrogen atoms may be substituted by halogen atoms), and X− represents (R9SO2)3C− wherein R9 represents a C1-4 aliphatic hydrocarbon group which is unsubstituted or substituted by a halogen atom.