In the present invention, an electro-optical condition generation unit includes: a condition setting unit that sets, as a plurality of electro-optical conditions, a plurality of electro-optical conditions in which the combinations of the aperture angle and the focal-point height for an electron beam are different; an index calculating unit that determines a measurement-performance index in the electro-optical conditions set by the condition setting unit; and a condition deriving unit that derives an electro-optical condition, including an aperture angle and a focal-point height, so that the measurement-performance index determined by the index calculating unit becomes a prescribed value.