A metal plate for manufacturing a deposition mask with reduced variation in dimension of through-holes wherein an average value of plate thicknesses of the metal plate in a longitudinal direction is within a ±3% range around a predetermined value. When an average value of the plate thicknesses of the metal plate in the longitudinal direction is represented as A, and a value obtained by multiplying a standard deviation of the plate thicknesses of the metal plate in the longitudinal direction by 3 is represented as B, (B/A)×100 (%) is ≤5%. When a value obtained by multiplying a standard deviation of the plate thicknesses of the metal plate in the width direction by 3 is represented as C, and a value of a plate thickness of the metal plate at a central portion in the width direction is represented as X, (C/X)×100(%) is ≤3%.