A method of inspecting an elongated metal plate is provided, including measuring longitudinal direction metal plate thicknesses, measuring width direction metal plate thicknesses, and selecting the metal plate that satisfies condition (1), (B/A)×100 (%) is 5% or less, A being an average value of the longitudinal direction metal plate thicknesses, and B being obtained by multiplying a standard deviation of the longitudinal direction metal plate thicknesses by 3, and that satisfies condition (2), (C/X)×100 (%) is 3% or less, C being a value obtained by multiplying a standard deviation of the width direction metal plate thicknesses by 3, and X being a central portion width direction metal plate thickness obtained when the width direction metal plate thicknesses are measured to calculate the standard deviation of the metal plate thicknesses in the width direction.