A thin magnifier structure with magnetic protective jacket, including a transparent magnifying member, a magnetic jacket and a pivot member. The transparent magnifying member integrally has a magnifier and is movably clipped and hidden in the magnetic jacket. The transparent magnifying member and the magnetic jacket are pivotally connected with each other via the pivot member, whereby the transparent magnifying member can be pivoted about the pivot member out of or into the magnetic jacket. When not used, the transparent magnifying member is clipped and hidden in the magnetic jacket, whereby the magnifier is protected from being scraped by any alien article. In use, the transparent magnifying member is pivoted about the pivot member out of the magnetic jacket. At this time, a user can hold the magnetic jacket with a hand to see an object through the magnifier without contaminating the magnifier. The thin magnifier structure is also usable as a bookmark.