In one embodiment, a method of obtaining a beam deflection shape includes using a plurality of beams to write a line pattern on a substrate by deflecting the plurality of beams, the plurality of beams being beams in the i-th row (i is an integer satisfying 1≤i≤m) among multiple charged-particle beams including beams of m rows and n columns (m and n are integers equal to or greater than two), the deflection being performed in such a manner that a writing area for a beam in the j-th column (j is an integer satisfying 1≤j≤n−1) is continuously adjacent to a writing area for a beam in the (j+1)th column, measuring a degree of unevenness of an edge of the line pattern, and obtaining a deflection shape of the beam based on the degree of unevenness.