A device for film thickness measurement and a method for film thickness measurement are disclosed. The device includes a planar indenter, a collecting unit and a processing unit. The planar indenter includes a base plate and a piezoelectric film layer. The collecting unit includes a plurality of collecting circuits evenly distributed above the piezoelectric film layer and spaced from each other. The collecting circuits are used for collecting current signals generated when the piezoelectric film layer deforms at positions corresponding to the collecting circuits. The processing unit is used for calculating a film thickness of the film sample to be measured based on the current signals collected by each of the collecting circuits.