PURPOSE: To improve a printing accuracy and to always uniformly print in a predetermined ruled range by measuring the thickness of a sheet to judge the number of set pages, calculating a suitable feeding correction on the basis of the judgement, and feeding the sheet on the basis of it.

CONSTITUTION: When a sheet 100 for a bankbook or the like is supplied, the sheet 100 is interposed between a lower measurement roller 9b and an upper measurement roller 9a. A distance from the roller 9b to the roller 9a or a dropping distance from an upper reference position is measured by a sheet thickness measuring CCD sensor 12, and this value is stored in a RAM. Then, this measured value is compared with second reference data of a sheet 2, and if the measured value is not larger than the data, the number of one correction step is stored as a correction amount in the RAM. On the other hand, if it is larger, the value is compared with a third reference data, and if it is not larger, the number of second correction step is stored in the RAM. Then, the sheet 100 is fed by a pair of feed rollers 2a and 2a' driven by a stepping motor to a printing hammer 4.