PURPOSE: To perform corrected exposure at a high speed by dividing the exposure to two stages, rough exposure and corrected exposure, and executing the corrected exposure with light whose energy is adjusted according to a difference between accumulated exposure up to the present and appropriate exposure.

CONSTITUTION: This device is provided with a monitoring device 8 for monitoring the energy of the light for exposing which is intermittently projected and a rotatable interference filter 11 which is a light quantity variable device 2 being a means for adjusting the energy of the light for exposing. The accumulated value of the energy outputted from the device 8 is compared with a desired exposure energy value so as to calculate the corrected energy quantity required for attaining the desired exposure energy value. In the case that the calculated result is smaller than the predicted maximum energy of one pulse, the energy quantity of one pulse is adjusted by the adjusting means to perform the corrected exposure. The corrected energy quantity is calculated again and the corrected exposure is repeated until the corrected energy quantity attains target accuracy.