A paper sheet storage unit comprising: a casing ; and a circulation unit that is accommodated in the casing to receive paper sheets transported into the casing by operating upon reception of a drive force from a motor and feed paper sheets stored therein to outside of the casing , wherein the casing includes a guide member that is configured to serve as a guide at a time of attaching or detaching the circulation unit to or from the casing by linearly and slidingly moving the circulation unit with respect to the casing , and the circulation unit includes a guided member , which is configure to detachably engage with the guide member , and to be guided to an installation completion position along the guide member in an engaged state, the circulation unit includes a circulation drum that is configured to spirally wind two tapes (T1-T4) around an outer periphery thereof in an overlapped state on each other and to feed each of the tapes (T1-T4) in a process of rotating in forward and reverse directions, and two bobbins that are configured to respectively feed each of the tapes (T1-T4) to the outer periphery of the circulation drum and to wind each of the tapes (T1-T4) in a process of rotating in forward and reverse directions, each of the tapes (T1-T4) forms a linear contact travel area (TA,TB) in which the tapes (T1-T4) come in contact with each other and transport a paper sheet, while placing the paper sheet therebetween, at a position immediately before moving to the outer periphery of the circulation drum , and a guide direction of the guide member to guide the guided member is parallel to the contact travel area (TA,TB). a casing ; and a circulation unit that is accommodated in the casing to receive paper sheets transported into the casing by operating upon reception of a drive force from a motor and feed paper sheets stored therein to outside of the casing , wherein the casing includes a guide member that is configured to serve as a guide at a time of attaching or detaching the circulation unit to or from the casing by linearly and slidingly moving the circulation unit with respect to the casing , and the circulation unit includes a guided member , which is configure to detachably engage with the guide member , and to be guided to an installation completion position along the guide member in an engaged state, the circulation unit includes a circulation drum that is configured to spirally wind two tapes (T1-T4) around an outer periphery thereof in an overlapped state on each other and to feed each of the tapes (T1-T4) in a process of rotating in forward and reverse directions, and two bobbins that are configured to respectively feed each of the tapes (T1-T4) to the outer periphery of the circulation drum and to wind each of the tapes (T1-T4) in a process of rotating in forward and reverse directions, each of the tapes (T1-T4) forms a linear contact travel area (TA,TB) in which the tapes (T1-T4) come in contact with each other and transport a paper sheet, while placing the paper sheet therebetween, at a position immediately before moving to the outer periphery of the circulation drum , and a guide direction of the guide member to guide the guided member is parallel to the contact travel area (TA,TB). <EOS>