PURPOSE: To enhance the treatment efficiency of a system, by performing control at the time of printing by comparing the information of the paper format of a printer read by a sensor and the information of the printing format stored in a table.

CONSTITUTION: A printer 1 returns the code read by a sensor to a printer control part 12 through a printer input/output control part 11. The printer control part 12 transmits the code of a slip paper format to a slip detection control part 73 when there is said code. A slip ID take-out control part 72 stores a table in a slip ID table region 71 and subsequently delivers the code of the printing format of the program concerned in the table to the slip detection control part 73. Two codes obtained are compared by the slip detection control part 73 and the comparing result is delivered to an error detection and judge control part 74 and, when said result is normal, the result is informed to a user program control part 51 to perform the output to the printer. When an error is generated, the comparing result is delivered to an error processing control part 23.