NOVELTY - The method comprises obtaining thin film particles by oxidizing graphite, dispersing the particles having a carbon skeleton in a liquid having a relative dielectric constant of greater than or equal to 15, and irradiating the thin film particles with light. The thin film particles have a thickness of 0.4-100 nm and a planar-direction size of greater than or equal to 20 nm. A dispersion of the thin film particles is applied to a substrate to obtain a thin-film layer made of the thin film particles, and then the entire surface of the thin film layer or a desired portion of the thin film layer is irradiated with the light.    USE - The method is useful for reducing thin film particles, which are useful in fine circuits (device or wiring), circuits for high temperatures (device or wiring), opto-electric conversion devices (solar cell and LED), semiconductor devices, exothermic matters, optical devices and stable recording materials.    ADVANTAGE - The method is capable of easily and economically manufacturing the thin film particles with high mobility and improved flexibility, where the thin film particles are lightweight and provide excellent lightness and bendability properties to an organic semiconductor.    DETAILED DESCRIPTION - The method comprises obtaining thin film particles by oxidizing graphite, dispersing the particles having a carbon skeleton in a liquid having a relative dielectric constant of greater than or equal to 15, and irradiating the thin film particles with light. The thin film particles have a thickness of 0.4-100 nm and a planar-direction size of greater than or equal to 20 nm. A dispersion of the thin film particles is applied to a substrate to obtain a thin-film layer made of the thin film particles, and then the entire surface of the thin film layer or a desired portion of the thin film layer is irradiated with the light. The light to be irradiated has a wavelength of 100-1100 nm. A resistivity of the thin film particles after the light irradiation is decreased to less than or equal to 10000 Omega cm.    DESCRIPTION OF DRAWING(S) - The drawing shows an atomic force microscope image of a bending portion of a thin film particle.