A thickness measurement device for a sheet-type medium comprises: a fixing frame (1), used for installing and bearing the following parts and components; a reference shaft (2), having two ends installed on the fixing frame (1) through bearings, wherein a reference roller (21) is fixedly fitted on the reference shaft (2); a detection shaft (3), wherein at least one floating support frame (31) having one end capable of rotating freely around the detection shaft (3) is arranged on the detection shaft (3), and a detection roller (32) and a signal generator (33) are arranged on the floating support frame (31); an elastic pressing plate (4), for pressing against the floating support frame (31) to keep an approaching trend between the detection roller (32) and the reference roller (21), wherein the elastic pressing plate (4) is composed of at least two elastic sheets; a signal sensor (5); and a data processing unit. By means of the device, system damping is provided through friction between the elastic sheets, an output signal impact peak value instantly caused by the fact that a front end of the sheet-type medium crushes into a floating support frame bearing and a power shaft meshing point at a certain speed is reduced, and the adjustment time of oscillation of an output signal is shortened.