To provide a measuring method, for the plated-film thickness of a lead frame, in which the plated-film thickness can be measured quickly, at low costs and in a noncontact manner.

Noncontact displacement meters 110 are arranged on one face side or both face sides of a sample 180. Displacements on the surface and the rear of the sample are measured. The difference in a height between a plated part 180B and a nonplated part 180A is found on the basis of obtained displacement data. The difference is regarded as a plated-film thickness. Concretely, triangulation-type laser displacement meters are used as the noncontact displacement meters 110, the noncontact displacement meters are arranged on both the surface and the rear of the sample, added data as obtained displacement data on the front and the rear are found, and the difference in the height between the plated part and the nonplated part is found on the basis of the data.