PURPOSE: To execute exposure in an extremely short time and to drastically reduce the cost of manufacture by irradiating a sample with light while a mask is moved when a shutter is under an open state.

CONSTITUTION: When the sample 9 is exposed, a light source which is not shown in a figure is turned on and the shutter 2 is irradiated with incident light 1. Next, a control signal is outputted to the shutter 2 and a motor 6 from an interlocking circuit 10 and the shutter 2 and the motor 6 are synchronized. That means, the motor 6 is driven under a state that the shutter 2 is closed and the mask 3 is moved in the direction of an optical path by it. In such a case, since the shutter is under the open state, the sample 9 is irradiated with the incident light 1 and it can be successively exposed. That means, since the exposure is executed while the focusing position of an optical system 7 with respect to the sample 9 is changed, the exposure equal to a conventional FLEX method is executed by one-time exposure and the sample whose flatness is deteriorated is exposed in an extremely short time.