A scanning transmission electron microscope (STEM) and method of aberration correction have autocorrelation function calculation means, aberration coefficient calculation means, and feedback control. At least two images are obtained by varying a value at which one of the electron optical means is set. The at least two images are autocorrelated. Iso-intensity lines are fit to aberration functions. Aberration coefficients are obtained based on aberration functions. The feedback controls the electron optical column.