An image forming device comprising: an image forming section which includes at least one recording head having nozzles from which ink is to be discharged, and for forming an image on a recording medium by discharging the ink from the nozzles; a scanning section configured to scan the image formed on one face of the recording medium by the image forming section; a conveying section configured to convey the recording medium in such a way that the recording medium passes by locations of the image forming section and the scanning section with one face of the recording medium facing the image forming section and the scanning section; an inverting section which is configured so as to, if the image is to be formed on each face of the recording medium by the image forming section, invert the recording medium having the image formed on one face thereof and to convey the recording medium to an upstream of the image forming section in a conveyance direction of the conveying section, and a changing section configured to change a condition relating to image formation by the image forming section based on a result of scanning of the image by the scanning section; wherein the scanning section is disposed downstream of the image forming section and upstream of the inverting section in the conveyance direction; and the image includes a test chart as a pattern image for detection of existence of clogging of the nozzles; the changing section is configured to change the condition relating to the ink discharge from the nozzles in such a way that, if the clogging is detected at any of the nozzles of the at least one recording head based on the result of the scanning of the pattern image by the scanning section, a missing part is covered by the ink discharged onto a neighborhood of the missing part on the recording medium, the missing part being a part onto which no ink is discharged due to the clogging of the any of the nozzles. an image forming section which includes at least one recording head having nozzles from which ink is to be discharged, and for forming an image on a recording medium by discharging the ink from the nozzles; a scanning section configured to scan the image formed on one face of the recording medium by the image forming section; a conveying section configured to convey the recording medium in such a way that the recording medium passes by locations of the image forming section and the scanning section with one face of the recording medium facing the image forming section and the scanning section; an inverting section which is configured so as to, if the image is to be formed on each face of the recording medium by the image forming section, invert the recording medium having the image formed on one face thereof and to convey the recording medium to an upstream of the image forming section in a conveyance direction of the conveying section, and a changing section configured to change a condition relating to image formation by the image forming section based on a result of scanning of the image by the scanning section; wherein the scanning section is disposed downstream of the image forming section and upstream of the inverting section in the conveyance direction; and the image includes a test chart as a pattern image for detection of existence of clogging of the nozzles; the changing section is configured to change the condition relating to the ink discharge from the nozzles in such a way that, if the clogging is detected at any of the nozzles of the at least one recording head based on the result of the scanning of the pattern image by the scanning section, a missing part is covered by the ink discharged onto a neighborhood of the missing part on the recording medium, the missing part being a part onto which no ink is discharged due to the clogging of the any of the nozzles.