The glass fiber of the present invention is formed of the glass composition including 50 to 60% SiO2, 0.1 to 10% Al2O3, 20 to 45% MgO+CaO+SrO+BaO, 0.5 to 20% TiO2, 0.1 to 10% ZrO2, and 0 to 2% Li2O+Na2O+K2O in terms of mol %, in which a BaO/CaO mol ratio is from 0.3 to 1.6.