An image forming apparatus comprising: image forming means for forming an image on a recording sheet, the recording sheet having a first surface and a second surface; light emitting means for emitting, by one light source, a first light beam in a first direction and a second light beam in a second direction different from the first direction; image capturing means (43, 43A, 43B, 44A 44SA, 44SB, 43L) for capturing an image of a first light-illuminated area illuminated with the first light beam on the first surface of the recording sheet as a first image, and an image of a second light-illuminated area illuminated with the second light beam on the first surface of the recording sheet as a second image, wherein the second light illuminated area is different to the first light-illuminated area, and wherein the first light illuminated area and the second light-illuminated area do not overlap each other, wherein the first light-illuminated area and the second light-illuminated area are on the same surface of the recording sheet; and control means for controlling an image forming condition for the image forming means based on information to be obtained from the first image and the second image about unevenness on the surface of the recording sheet; characterised in that a first straight line including a ray in a center of the first light beam illuminating the first light-illuminated area and a second straight line including a ray in a center of the second light beam illuminating the second light-illuminated area intersect with each other, when each straight line is projected on the surface of the recording sheet. image forming means for forming an image on a recording sheet, the recording sheet having a first surface and a second surface; light emitting means for emitting, by one light source, a first light beam in a first direction and a second light beam in a second direction different from the first direction; image capturing means (43, 43A, 43B, 44A 44SA, 44SB, 43L) for capturing an image of a first light-illuminated area illuminated with the first light beam on the first surface of the recording sheet as a first image, and an image of a second light-illuminated area illuminated with the second light beam on the first surface of the recording sheet as a second image, wherein the second light illuminated area is different to the first light-illuminated area, and wherein the first light illuminated area and the second light-illuminated area do not overlap each other, wherein the first light-illuminated area and the second light-illuminated area are on the same surface of the recording sheet; and control means for controlling an image forming condition for the image forming means based on information to be obtained from the first image and the second image about unevenness on the surface of the recording sheet; characterised in that a first straight line including a ray in a center of the first light beam illuminating the first light-illuminated area and a second straight line including a ray in a center of the second light beam illuminating the second light-illuminated area intersect with each other, when each straight line is projected on the surface of the recording sheet.