The charged particle beam device has a problem that a symmetry of equipotential distribution is disturbed near the outer edge of a specimen, an object being evaluated, causing a charged particle beam to deflect there. An electrode plate installed inside the specimen holding mechanism of electrostatic attraction type is formed of an inner and outer electrode plates arranged concentrically. The outer electrode plate is formed to have an outer diameter larger than that of the specimen. The dimensions of the electrode plates are determined so that an overlapping area of the outer electrode plate and the specimen is substantially equal to an area of the inner electrode plate. The inner electrode plate is impressed with a voltage of a positive polarity with respect to a reference voltage and of an arbitrary magnitude, and the outer electrode is impressed with a voltage of a negative polarity and of an arbitrary magnitude.