PURPOSE: To securely avoid printing in excess of the size of a sheet by providing a means to control the start of printing a picture on a sheet according to the detection of the leading edge of the sheet and a means to control the end of printing the picture on the sheet according to the detection of the trailing edge of the sheet.

CONSTITUTION: When the leading edge of a sheet 1 is detected by a detection means 5 on a conveyance route 4, the control to start printing for the sheet is carried out by a means 6, and as a result, printing is started with a desired position on the leading edge of the sheet. Thereafter, when the trailing edge of the sheet 1 is detected by a detection means 7, the control to end printing for the sheet 1 is carried out by a means 8. Consequently, printing in excess of the size of a sheet can be avoided.