The invention provides an zoom optical system and an image pickup apparatus having the same. The zoom optical system comprises a prism component which comprises in order from an object side, an entrance surface having negative refracting power, and a reflecting surface, and movable groups which are movable when either of zooming or focusing is carried out. An image pickup apparatus is provided with the zoom optical system. Thereby, thinning of the image pickup apparatus can be attained sufficiently, and it is possible to shorten the full length of the optical system furthermore, while keeping a moderate zooming ratio. |