An imaging lens system includes an optical path folding member including a forwardmost reflective surface disposed closest to an object side, a rearmost reflective surface disposed closest to an imaging plane, and a rear reflective surface disposed to form an acute angle with the rearmost reflective surface and configured to reflect light reflected by the rearmost reflective surface to the imaging plane, and a first lens group disposed on an object side of the forwardmost reflective surface or an image side of the forwardmost reflective surface, wherein an angle between a first virtual plane including the forwardmost reflective surface and a second virtual plane including the rearmost reflective surface is 15 to 27 degrees.