PURPOSE: To provide bead core structure enabling light weight in addition to satisfying strength as a tire, shape retainability and fitting force to a rim by using fiber cords with high tension such as Aramid fiber cords in combination with steel wire cords as the constituent wire material of a bead core.

CONSTITUTION: An annular bead core 1 disposed at the bead part B of a tire is formed of steel wires 3a and fiber cords 3b with high tension such as Aramid fiber cords so as to have steel wires 3a in at least a first layer 1a on the core inner diameter side. The bead core 1 thereby has strength against shearing stress generated to the winding start part by compressive force caused by fitting to a rim so as to prevent the lowering of fitting force.