To provide a zoom gear train with which a camera having a zoom mechanism can be made more compact.

The gear train comprises a plurality of gears 1 to 9. A third double gear 5, idol gear 6, first and second gears 7 and 8, and a final gear 9 are incorporated in a space formed by a zoom lens barrel 21, a film cartridge chamber outer frame 22, and the front panel and the bottom surface panel of the cover 23 of the camera. The large diameter gear 5a of the third double gear 5 is placed at the front side of a small diameter gear 5b. The second gear 8 with a larger diameter than that of the first gear 7 is placed at the front side of the first gear 7. The final gear 9 with a long central shaft is placed between the bottom surface panel and the zoom lens barrel 21. Thus, an area seen from the object side of the camera and thickness in a longitudinal direction can be made more compact.