A non-printed paper supply apparatus for a single-side printer for reversing a stacked paper, in which a plurality of sheets of paper has been stacked and one side of each paper sheet has been printed, so that a non-printed surface comes to an upper surface and supplying the stacked paper to a printer again, comprising: two pallets (21, 22) configured to sandwich and hold the a stacked paper from upper and lower sides; a plurality of alignment holding tools configured to be provided between the pallets (21, 22) and be adjusted according to a volume of the a stacked paper; a pair of fastening and reversing tools configured to include reversing bars in which reversing shafts for reverse are formed on sides of the pallets (21, 22) opposite to each other; and a pair of reverse assisting stands configured to pivotally support the reversing shafts of the fastening and reversing tools, wherein a fixing tool, which attaches/detaches the alignment holding tool and the fastening and reversing tool with the respective upper/lower pallets (21, 22), includes receiving tools which are buried and fixed to edge frames of the upper/lower pallets (21, 22) and fixing pins to be inserted into and fixed to the receiving tools, characterized in that the fixing pins are inserted into the receiving tools via holes formed on both ends of the alignment holding tool and edges of a rack (413, 413') of the fastening and reversing tool, and the alignment holding tool and the fastening and reversing tool are attached/detached with the respective upper/lower pallets (21, 22) by slightly rotating the fixing pin in a clockwise or counterclockwise direction and fixing; wherein the receiving tool has a plate in which an insertion hole having a circular hole and a hole for projection connected to the edge of the circular hole is bored and a substantially cylindrical guide tube which has a slit groove having a width to be fit to a position of the hole for projection connected to the circular hole formed on the plate, and the plate and the substantially cylindrical guide are provided to be fixed to each other; wherein in the fixing pin, a projection which is inserted into the slit groove is provided at a front end part of a pin body, and a handle part is provided at an end part. two pallets (21, 22) configured to sandwich and hold the a stacked paper from upper and lower sides; a plurality of alignment holding tools configured to be provided between the pallets (21, 22) and be adjusted according to a volume of the a stacked paper; a pair of fastening and reversing tools configured to include reversing bars in which reversing shafts for reverse are formed on sides of the pallets (21, 22) opposite to each other; and a pair of reverse assisting stands configured to pivotally support the reversing shafts of the fastening and reversing tools, wherein a fixing tool, which attaches/detaches the alignment holding tool and the fastening and reversing tool with the respective upper/lower pallets (21, 22), includes receiving tools which are buried and fixed to edge frames of the upper/lower pallets (21, 22) and fixing pins to be inserted into and fixed to the receiving tools, characterized in that the fixing pins are inserted into the receiving tools via holes formed on both ends of the alignment holding tool and edges of a rack (413, 413') of the fastening and reversing tool, and the alignment holding tool and the fastening and reversing tool are attached/detached with the respective upper/lower pallets (21, 22) by slightly rotating the fixing pin in a clockwise or counterclockwise direction and fixing; wherein the receiving tool has a plate in which an insertion hole having a circular hole and a hole for projection connected to the edge of the circular hole is bored and a substantially cylindrical guide tube which has a slit groove having a width to be fit to a position of the hole for projection connected to the circular hole formed on the plate, and the plate and the substantially cylindrical guide are provided to be fixed to each other; wherein in the fixing pin, a projection which is inserted into the slit groove is provided at a front end part of a pin body, and a handle part is provided at an end part.