PURPOSE: To increase an entry area of a mark utilized as the information on a slip while also reduce an entry time, by providing one skew check mark in an area on the slip and checking and presence of a diagonal feed of the slip.

CONSTITUTION: In the slip diagonal feed check method checking for whether a slip N is diagonally fed or not with respect to its conveyed direction α, the slip, in which at least one skew check mark CH for checking a diagonal feed is printed in an information mark entry area on the slip, is used to read the mark CH by a mark read part. Further at time to read the mark CH, a mark CH read time signal is generated in a control unit to perform a diagonal feed check of the slip at generation of the mark CH read time signal by whether the mark read is performed or not. Accordingly, as an entry area of the mark utilized as the information on the slip increases, also an entry time is reduced, further a specific sensor is not utilized, and reliability of a check result is improved.