An adaptor includes an adaptor main body capable of being mounted with respect to a liquid accommodation body mounting portion of a printer to which an ink cartridge configured to accommodate ink is mounted in an attachable or detachable manner; a memory cell MC that is updated by a control portion of the printer, and maintains information about whether or not the printing operation is possible in the printer; an electrical terminal that is used in communication between the memory cell and the printer; and an operation button that outputs an update signal that updates information about whether or not the printing operation is possible to information permitting the printing operation of the printer with respect to the memory cell, when the information about whether or not the printing operation is possible maintained in the memory cell does not permit the printing operation of the printer.