To reduce complexity of deflection control work, increase in aberration of electron beam, effect to resolution and instability of electron beam.

A differential pumping float head 4 non-contact floating the front part of an electron beam emission hole 26 from an electron beam irradiator 3 and restrictively holding in vacuum has a vacuum seal valve 31 opening and closing an electron beam transmission hole 30. The vacuum seal valve 31 forms an open state in which the electron beam transmission hole 30 of the differential evacuation float head 4 and an arrange state arranging an electron beam transmission hole 32 with smaller inner diameter than that of the electron beam emission hole 26 and the electron beam transmission hole 30 of the differential pumping float head 4, in a light path position of the electron beam 2. The diameter of the electron beam transmission hole 30 is made sufficiently large. When the optical axis of the electron beam is controlled, the electron beam position is controlled with a parallel movement control of the optical axis by opening the vacuum seal valve 31 and making the margin large.

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