To provide a glass composition for glass fiber having a low dielectric loss tangent, suppressing the occurrence of phase separation, having a reduced viscosity at high temperatures, and reducing the occurrence of striae. The glass composition for glass fiber includes 52.0 to 57.5% by mass of SiO 2 , 19.5 to 25.5% by mass of B 2 O 3 , 8.0 to 13.0% by mass of Al 2 O 3 , 0 to 2.0% by mass of MgO, 0 to 6.0% by mass of CaO, 0.5 to 6.5% by mass of SrO, and 0.1 to 3.0% by mass of TiO 2 , the ratio of Al 2 O 3 to B 2 O 3 is 0.35 to 0.54, and the content SI of SiO 2 , the content B of B 2 O 3 , the content M of MgO, the content C of CaO, the content SR of SrO, and the content T of TiO 2 satisfy the following formula (1): 6.90 ≤ 100 × (B/SI) 2 × {SR/(C+SR)} 2/3 × {T/(M+T)} 1/2 ≤ 12.30 (1).