According to Genesis, Noah’s eldest son was Shem.
Genesis names Noah’s sons as Shem, Ham, and Japheth. In Genesis 10:21, Shem is described in wording commonly translated as the older brother of Japheth, and many traditional readings therefore place Shem first among the brothers. The three sons and their wives accompany Noah into the ark during the flood narrative.
Shem is especially important in the genealogical material that follows. Genesis traces a line from Shem to Abram, later known as Abraham, making Shem a major ancestor in the biblical family history. His name also appears in the term “Semitic,” a modern linguistic and historical label derived from the biblical name, though the term has broader scholarly uses.
A common confusion is to treat Ham as the eldest because his story receives attention after the flood. Genesis’s family list begins with Shem, Ham, and Japheth, and the answer asked for here is Shem.