Disclosed is a printing apparatus that can prevent the occurrence of a transport error and prevent useless printing even when the sheet size of the actually fed sheet is different from the sheet size specified in the printing setting. The printing apparatus forms an image on one side of a recording medium first and then forms an image on another side of the recording medium. A determination section determines the medium length of the recording medium, and a control section causes the recording medium to be ejected to a sheet ejection port after the image is formed on the one side of the recording medium, when the determined medium length is outside of a preset threshold range.