To provide: a ticket printer and a code-reading program, which are capable of reliably detecting a ticket ID and the like; and ticket-issuing roll paper.

An exemplary ticket printer includes a code-reading part for reading a code printed on a sheet, where the code consisting of a plurality of m-by-n unit code blocks (where parallel m-columns in parallel with transport direction of the sheet, and n-rows continuously in the transport direction, are printed (where m and n are natural numbers of 2 or larger)). Here, at least one code of m-column constituting a unit code block of the unit code blocks, the unit code block that is initially scanned in the transport direction, is a black mark, enabling the code-reading part to detect a beginning of the unit code block thereby to read code information.