This charged-particle beam device changes conditions for combining an intensity ratio between upper and lower deflectors and rotation angles of the deflectors in multiple ways when obtaining images having different pixel sizes in the vertical and horizontal directions. Then, the charged-particle beam device determines an optimal intensity ratio between the upper and lower deflectors and rotation angles of the deflectors on the basis of variations in size value measured in the larger pixel size direction (Y-direction) of the image. As a result, it is possible to extend the field of view in the Y-direction while reducing deflection aberrations when measuring at high precision in the X-direction.