A charged beam lithography system includes a charged particle gun for generating charged beams, a main deflecting system and a sub-deflecting system for deflecting the charged beams generated by the charged particle gun, and a control computer. The charged beam lithography system is designed to cause the surface of a substrate to be irradiated with the charged beams from the charged particle gun while continuously moving a stage, to write a desired pattern for each of stripes defined by the maximum deflection widths of the main deflecting system and the sub-deflecting system. The charged beam lithography system further comprises: a real time proximity effect correcting circuit for calculating an optimum dosage for each of the stripes by correcting the dosage of the electron beams in view of the influence of the proximity effect; and a cash memory for storing the optimum dosage data for at least two of the stripes. Thus, the charged beam lithography system is designed to shift a divided form of the whole written region using the stripes at each wiring number of times, by a predetermined distance from a predetermined reference position in a direction perpendicular to a stage continuous moving direction, while selectively extracting the optimum dosage data from the cash memory so as to correspond to each of written stripes at each writing number of times, to write patterns. During the writing operation, the optimum dosage data corresponding to the next region to be written are transferred from the real time proximity effect correcting circuit to the cash memory, and the real time proximity effect correcting circuit calculates optimum dosages for the stripes corresponding to regions to be written after next and thereafter.