the tension member for a belt of this invention is made from a glass cord . first twist yarns of this glass cord are obtained by paralleling and twisting a plurality of fiber bundles , each including a large number of glass filaments , by a predetermined first twist number . the fiber bundles are previously soaked with a treatment liquid including a mixture of rubber latex and an initial condensation product of resorcinol and formalin as a main component and then heated . the glass cord is fabricated by paralleling a predetermined number of the first twist yarns and twisting them by a predetermined final twist number , so as to squeeze and substantially eliminating spaces among the first twist yarns . accordingly , the belt including this glass cord as the tension member can achieve good water resistance because externally intruding water is prevented from being held within the belt .