PURPOSE: To express a gradation even against a photosensitive body having any photosensitive characteristic, irrespective of negative and positive, without using an optical image forming system, by providing an optical radiation mechanism, a variable density filter which has been made to come into contact with the optical radiation mechanism, and the photosensitive body which has been made to come into contact with the variable density filter.

CONSTITUTION: A light beam which has been radiated from a light emitting element array 10, or a light beam which has radiated from a light source 11 and has passed through a light quantity control element array 12 passes through a variable density filter 2, and irradiated to a photosensitive body 3 which has brought into contact with the variable density filter 2. When the title printer is constituted so that a density distribution of the variable density filter 2 corresponding to each dot of the light emitting element array 10 or the light quantity control element array 12 becomes denser gradually toward the periphery (x) from the center 0, a transmission light in the peripheral part of the dot can be decreased, therefore, without using an image forming optical system such as a selfoc lens, etc., an influence exerted on the adjacent dot can be suppressed. In this case, by changing a density distribution of the variable density filter, a shape of an irradiated energy distribution on the photosensitive body is changed, and by controlling an intensity or a radiation time of a radiant ray, its magnitude can be controlled continuously.