PURPOSE: To surely detect existence of a sheet body with ease by means of simple constitution.

CONSTITUTION: An unloading device is provided with a mounting plate 16, in which plural sheet bodies 12 are placed and a notch part 14 extending to the inside of the sheet body mounting face is arranged, and a sheet body arranging mechanism 18, which moves forward/backward along the face direction of the sheet body 12, presses the end faces of the sheet bodies 12 so as to position them in the layer position, and can be inserted into the notch part 14 in the mounting plate 16. The unloading device is also provided with a sheet body existence detecting mechanism 20 which is arranged in the sheet body arranging mechanism 18 and detects whether the sheet body 12 exists on the mounting plate 16 or not when the sheet body arranging mechanism 18 is inserted into the notch part 14.