PURPOSE: To make a dislocation of superposed colors wich are applied less, a conveyance accracy high and a conveyance load of a blank form sheet less even in a curved route in a compact device.

CONSTITUTION: After a sheet 8 passes over a ridge line 6a of a paper guide from a sheet feeding roller 2b and the sheet 8 is printed between a thermal head 3 and a platen 4, the thermal head 3 returns to a predetermined position, the sheet is sent reversely by a conveyance means 5 and by generating a spontaneous deflection with the ridge line 6a of a paper guide which is used as a supporting point, a conveyance load is lessened and, by returning the sheet at the position of a sheet feeding roller 2a, a printing by reciprocating conveyance with high accuracy is executed.