A thickness detection device for sheet-type medium, comprising: a fixing frame, configured to mount and bear a reference shaft and a detection assembly shaft; a reference shaft, which has two ends mounted on the fixing frame via bearings, and one end of which is driven by power, a reference roller being fixedly sleeved on the reference shaft; and a detection assembly shaft, which is fixedly mounted on the fixing frame and has a relatively fixed distance from the reference shaft, at least one detection roller being provided on the detection assembly shaft, and the detection roller being in an elastic contact with the reference roller; wherein the detection roller is sleeved on the detection assembly shaft by a bracket, the bracket has an elongated hole through which the bracket is sleeved on the detection assembly shaft; an elastic element is provided between an end of the elongated hole and the detection assembly shaft, so that the elastic element allows the detection assembly shaft to elastically maintain a certain distance from the end of the elongated hole; and so that the elastic element applies an action force on the bracket towards the reference shaft, to enable the detection roller to be in an elastic contact with the reference roller; and one side of the detection roller, which side is away from the reference roller, is provided with a distance detector adapted to achieve the thickness detection of the sheet-type medium passing through the detection passage defined by the detection roller and the reference roller, and the distance detector is fixedly arranged on the fixing frame and directly faces the detection roller. a fixing frame, configured to mount and bear a reference shaft and a detection assembly shaft; a reference shaft, which has two ends mounted on the fixing frame via bearings, and one end of which is driven by power, a reference roller being fixedly sleeved on the reference shaft; and a detection assembly shaft, which is fixedly mounted on the fixing frame and has a relatively fixed distance from the reference shaft, at least one detection roller being provided on the detection assembly shaft, and the detection roller being in an elastic contact with the reference roller; wherein the detection roller is sleeved on the detection assembly shaft by a bracket, the bracket has an elongated hole through which the bracket is sleeved on the detection assembly shaft; an elastic element is provided between an end of the elongated hole and the detection assembly shaft, so that the elastic element allows the detection assembly shaft to elastically maintain a certain distance from the end of the elongated hole; and so that the elastic element applies an action force on the bracket towards the reference shaft, to enable the detection roller to be in an elastic contact with the reference roller; and one side of the detection roller, which side is away from the reference roller, is provided with a distance detector adapted to achieve the thickness detection of the sheet-type medium passing through the detection passage defined by the detection roller and the reference roller, and the distance detector is fixedly arranged on the fixing frame and directly faces the detection roller.