Abstract: The present invention provides a printing apparatus which can detachably mounted to a main machine and which is driven by a drive source independently from the main machine and is adapted to effect printing of a sheet conveyed from the main machine apparatus body, the printing apparatus having a sheet detect mechanism for detecting presence/absence of the sheet conveyed from the main machine, a sheet convey mechanism disposed at a downstream side of the sheet detect mechanism in a conveying direction within a sheet convey path, a print mechanism for effecting printing on the sheet conveyed by the sheet convey mechanism, and a drive control mechanism for controlling driving of the sheet convey mechanism and the print mechanism on the basis of a sheet detect signal from the sheet detect mechanism.