A projection lens, which has a first group of lenses having a negative power and a second group of lenses having a positive power, sequentially arranged from an enlargement side to a reduction side, satisfying the following conditional expressions through, and having a field angle of about 110\xb0 or more: 25. When the second fitting component is displaced into contact with the stepped wall surface during fitting pull-up, the stepped wall surface assists in separating the first fitting component from the second fitting component upon fitting disassembly. An operating hole of the screw is illuminated by the annular light source so that no shadow forms to vividly photograph a hole bottom of the operating hole with the CCD camera.