Method of calculating deflection aberration correcting voltage and charged particle beam writing method

A method of obtaining a deflection aberration correcting voltage, comprising:

• writing predetermined patterns at a plurality of focus height positions such that a dose is used as a variable for each of the plurality of focus height positions;
• measuring dimensional variations of width sizes of the predetermined patterns written at the plurality of focus height positions such that the dose is used as the variable for each of the plurality of focus height positions;
• calculating effective resolutions of the written predetermined patterns by using the dimensional variations;
• and
• on the basis of a focus height position at which a minimum effective resolution of the predetermined patterns is obtained, calculating a correcting voltage to correct deflection aberration and outputting the correcting voltage, wherein the correcting voltage is used when a charged particle beam is deflected.