A printing apparatus, which is capable of double-face printing to print images on both sides of a recording sheet, comprising: a printing unit, which is configured to print an image on one of the both sides of the recording sheet; a sheet feeder, which is configured to feed the recording sheet to the printing unit; a discharge unit, in which the recording sheet with the image printed thereon is settled; a sheet path, which includes a feeding path to guide the recording sheet fed from the sheet feeder to the printing unit, and a discharge path to guide the recording sheet passing through the printing unit to the discharge unit; a manual sheet inlet, through which a recording sheet is manually inserted in the printing apparatus by a user; and a manual sheet path, which is configured to merge into the sheet path at a merging point being in an upstream position with respect to the printing unit along the direction of conveying the recording sheet and guide the manually-inserted recording sheet to the merging point; characterized in that: the sheet path includes a reversing path diverging from the discharge path and merging into the feeding path at an upstream position with respect to the printing unit along a direction of conveying the recording sheet, the sheet path guiding the recording sheet therealong and reversing the recording sheet by use of the reversing path and reverse-conveyance during a double-face printing operation; and the apparatus further comprises: a detecting unit, which is configured to detect a manually-inserted recording sheet being fed through the manual sheet inlet; a judging unit, which is configured to judge as to whether the detecting unit has detected that a manually-inserted recording sheet is being fed through the manual sheet inlet while the double-face printing operation is being conducted with a preceding recording sheet; and a conveyer controller unit, which is configured to convey the preceding recording sheet in the double-face printing operation to the discharge unit without reversing the preceding recording sheet by use of the reversing path and reverse-conveyance when the judging unit judges that the detecting unit detects the manually-inserted sheet while the printing apparatus is conducting the double-face printing operation with the preceding recording sheet a printing unit, which is configured to print an image on one of the both sides of the recording sheet; a sheet feeder, which is configured to feed the recording sheet to the printing unit; a discharge unit, in which the recording sheet with the image printed thereon is settled; a sheet path, which includes a feeding path to guide the recording sheet fed from the sheet feeder to the printing unit, and a discharge path to guide the recording sheet passing through the printing unit to the discharge unit; a manual sheet inlet, through which a recording sheet is manually inserted in the printing apparatus by a user; and a manual sheet path, which is configured to merge into the sheet path at a merging point being in an upstream position with respect to the printing unit along the direction of conveying the recording sheet and guide the manually-inserted recording sheet to the merging point; characterized in that: the sheet path includes a reversing path diverging from the discharge path and merging into the feeding path at an upstream position with respect to the printing unit along a direction of conveying the recording sheet, the sheet path guiding the recording sheet therealong and reversing the recording sheet by use of the reversing path and reverse-conveyance during a double-face printing operation; and the apparatus further comprises: a detecting unit, which is configured to detect a manually-inserted recording sheet being fed through the manual sheet inlet; a judging unit, which is configured to judge as to whether the detecting unit has detected that a manually-inserted recording sheet is being fed through the manual sheet inlet while the double-face printing operation is being conducted with a preceding recording sheet; and a conveyer controller unit, which is configured to convey the preceding recording sheet in the double-face printing operation to the discharge unit without reversing the preceding recording sheet by use of the reversing path and reverse-conveyance when the judging unit judges that the detecting unit detects the manually-inserted sheet while the printing apparatus is conducting the double-face printing operation with the preceding recording sheet a detecting unit, which is configured to detect a manually-inserted recording sheet being fed through the manual sheet inlet; a judging unit, which is configured to judge as to whether the detecting unit has detected that a manually-inserted recording sheet is being fed through the manual sheet inlet while the double-face printing operation is being conducted with a preceding recording sheet; and a conveyer controller unit, which is configured to convey the preceding recording sheet in the double-face printing operation to the discharge unit without reversing the preceding recording sheet by use of the reversing path and reverse-conveyance when the judging unit judges that the detecting unit detects the manually-inserted sheet while the printing apparatus is conducting the double-face printing operation with the preceding recording sheet