世界纪元（拉丁语：Anno Mundi，缩写为 AM 或 A.M.），又译为创世纪年、创世纪元，一种根据旧约圣经对于世界创造观点的纪年方式。在希伯来历与拜占庭历（Byzantine calendar）中都使用这个纪年法。它有两种元年，一个是西元前5500年，另一个则是采用前4000年。

西元前5500年的说法，根据希腊七十士译本。前4000年的说法，则是根据马所拉文本。

Anno Mundi (Latin for "in the year of the world"; Hebrew: לבריאת העולם, "from the creation of the world"), abbreviated as AM or A.M., or Year After Creation, is a calendar era based on the biblical accounts of the creation of the world and subsequent history. While numerous efforts have been made to determine the biblical date of Creation, yielding varying results, two in particular have established epochs for significant calendars, including one that is still in use today.