To carry out highly precise printing to a predetermined part of a workpiece without printing failures brought out, and to detect generation of printing failures.

The workpiece is detected by a passing confirmation sensor 24, and a passing confirmation signal is outputted to a trigger signal hold circuit 30. Then, the workpiece is detected by a trigger sensor 26, and a trigger signal is outputted to the trigger signal hold circuit 30. Counting by a counter 32 is started on the basis of the trigger signal. At a time point when the counting reaches a predetermined count value, a printing part 14 is controlled by a printing control circuit 34 to carry out predetermined printing to the workpiece. In this case, wrong detection of the workpiece after the workpiece is detected by the trigger sensor 26 can be avoided by holding the trigger signal by the trigger signal hold circuit 30. Holding of the trigger signal by the trigger signal hold circuit 30 is released by means of the passing confirmation signal by the passing confirmation sensor 24. Therefore, printing control can be carried out by using the trigger signal detected after the passing confirmation signal is detected, as a correct detection signal of the workpiece.