PURPOSE: To decrease the number of sensors to be used and reduce the cost by performing idling conveyance when a power supply is turned ON, using a detecting sensor for performing the error detection of the passage of paper to be conveyed, and judging the presence or absence of the reception of the paper based on the result of the detection of the paper within a specified time.

CONSTITUTION: A sheet of recording paper 1 is pushed to a thermal head 2 with a roller 3 and conveyed. The picture information is printed with the thermal head 2. The recording paper 1 after the printing passes through guides 4 and 5, and the paper is detected when the paper passes on a photosensor 8. At this time, the count-down of the time, during which the recording paper 1 must reach a photosensor 8 from the printing part 2 after the start of the printing, is started with a conveying-time counting part 12. When the counted time has elapsed by the specified time, the occurrence of the passing-paper jam is judged with a passing-paper-error judging part 14. Idling conveyance is performed when a power supply is turned ON. When the paper is not detected within the specified time with the photosensoe 8, it is judged that the paper is not stored.