An apparatus for preprocessing paper sheets, including: a material remover that is configured to remove a material from a paper sheets assembly including a plurality of paper sheets strapped by the material; a detector located at an upstream side than the material remover, that is configured to detect an information of the paper sheets assembly; a controller that is configured to decide whether the paper sheets assembly satisfies a predetermined specification, based on the information detected by the detector; and a display, if the controller decides the paper sheets assembly does not satisfy the predetermined specification, that is configured to display a reason to decide the paper sheets assembly does not satisfy the predetermined specification; wherein the detector equips an imaging part that is configured to image the paper sheets assembly, and wherein the controller is configured to detect a winding method of the material based on an image information of the paper sheets assembly imaged by the imaging part, and, if the winding method is different from a predetermined winding method, the controller is configured to decide the paper sheets assembly does not satisfy the predetermined specification; and wherein the material includes a strapping material to strap the plurality of paper sheets as a strap, and a bundling material to bundle a plurality of straps as a bundle, the paper sheets assembly is the bundle, and the material remover equips a bundling material remover that is configured to remove the bundling material from the bundle, and a strapping material remover that is configured to remove the strapping material from the strap, characterized in that when the bundling material is detected to bundle a part of the straps included in the bundle, the controller is configured to decide that the bundle does not satisfy the predetermined specification. a material remover that is configured to remove a material from a paper sheets assembly including a plurality of paper sheets strapped by the material; a detector located at an upstream side than the material remover, that is configured to detect an information of the paper sheets assembly; a controller that is configured to decide whether the paper sheets assembly satisfies a predetermined specification, based on the information detected by the detector; and a display, if the controller decides the paper sheets assembly does not satisfy the predetermined specification, that is configured to display a reason to decide the paper sheets assembly does not satisfy the predetermined specification; wherein the detector equips an imaging part that is configured to image the paper sheets assembly, and wherein the controller is configured to detect a winding method of the material based on an image information of the paper sheets assembly imaged by the imaging part, and, if the winding method is different from a predetermined winding method, the controller is configured to decide the paper sheets assembly does not satisfy the predetermined specification; and wherein the material includes a strapping material to strap the plurality of paper sheets as a strap, and a bundling material to bundle a plurality of straps as a bundle, the paper sheets assembly is the bundle, and the material remover equips a bundling material remover that is configured to remove the bundling material from the bundle, and a strapping material remover that is configured to remove the strapping material from the strap, characterized in that when the bundling material is detected to bundle a part of the straps included in the bundle, the controller is configured to decide that the bundle does not satisfy the predetermined specification.