from the wide end arrives at about 50 u00b0 from the wide end and that the relative distance becomes small in a zooming area where the turning angle exceeded 50 u00b0 that is an area near the tele end thus in a phase of rotating by a half of the zoom turning angle towards the tele end from the wide end the distance between the third group lens barrel and moving diaphragm continues monotone increase in a phase of arriving at about one thirds of the zoom turning angle from the tele end that is at an angular range which is smaller than a half and larger than one fourth the distance between the third group lens barrel and moving diaphragm begins monotone decrease and the distance between the third group lens barrel and moving diaphragm in a phase of arriving at the tele end becomes shorter than the distance between the third group lens barrel and moving diaphragm in the wide end in order to obtain a suitable projection image near the tele end in optical performance the zoom lens barrel of this embodiment when used as a projector lens of a projection apparatus is made to have such construction that omits ambient light flux by shortening the distance between the third group lens barrel 3 and moving diaphragm 8 near the tele end in addition in locations other than the vicinity of the tele end since it is not necessary to.