1. An image forming apparatus that includes an image carrier for carrying a toner image on a surface thereof, an image forming unit for forming the toner image on the image carrier, a transfer unit for transferring the toner image on the image carrier onto a recording medium, and a fixing unit for fixing the toner image on the recording medium, the image forming apparatus comprising: a toner-image detecting unit that detects the toner image on the image carrier; a fixed-image detecting unit that detects the toner image fixed on the recording medium; a first image adjusting unit that forms an image adjustment test pattern on the image carrier, causes the toner-image detecting unit to detect the image adjustment test pattern on the image carrier, controls the image adjustment test pattern on the image carrier not to be transferred onto the recording medium, and adjusts an image forming condition on the basis of a detection value of the image adjustment test pattern detected by the toner-image detecting unit; and a second image adjusting unit that forms an image adjustment test pattern on the image carrier, and after the toner-image detecting unit detects the image adjustment test pattern on the image carrier, transfers and fixes the image adjustment test pattern on a recording medium, or again forms an image adjustment test pattern on the image carrier and transfers and fixes the image adjustment test pattern formed on the image carrier on a recording medium, causes the fixed-image detecting unit to detect the image adjustment test pattern fixed on the recording medium, and adjusts an image forming condition on the basis of a detection value of the image adjustment test pattern detected by the toner-image detecting unit and a detection value of the image adjustment test pattern detected by the fixed-image detecting unit, wherein the toner-image detecting unit and the fixed-image detecting unit are arranged so that positions of them in a main scanning direction perpendicular to a conveying direction of the recording medium are aligned.