An attachment used for an apparatus for attaching a tag-attaching pin utilizing a sheet of tag-attaching pins in which a plurality of tag-attaching pins is provided. Each pin has a filament section, an inserting head section provided at one end of the filament section, and a socket section or a holding section provided at the another end of the filament section. The pins are mutually arranged in parallel configuration and at least the inserting head section, the socket section, or the holding section are connected to connecting bars. The attachment is provided with a connecting portion detachably coupled with a coupling means formed on a side wall surface of the apparatus and a tag attaching pin controlling means, which is provided on the side wall surface of the apparatus and extends upward from a top surface of the apparatus. A connecting bar controlling means can control an arranged locus configuration of the connecting bars of the sheet and is formed on at least a portion of the tag attaching pin controlling means.