To improve the accuracy of boring positions of a plurality of holes bored along the transfer direction of a sheet.

A sheet boring device 119A comprises: a sheet transfer roller pair 51 for transporting a sheet; a punch 61 and a die 62 for sequentially boring a plurality of holes along the sheet transfer direction of the sheet S transported by the sheet transfer roller pair; a punched hole detection sensor 32 for detecting the holes bored by the punch and the die at the downstream side of the sheet transfer direction of the punch and the die. A CPU makes the punch and the die perform boring motions at prescribed timing by the detection of the holes of the sheet by the punch and the die, and the next hole is bored at the sheet.