PURPOSE: To provide filter a glass for cutting near-infrared rays which is excellent in chemical durability, while holding the sharp near-infrared ray cutting characteristic, and is high in the thermal shock resistance.

CONSTITUTION: This filter glass contains, by wt., 46-70% P2O5, 0.2-20% AlF3, 1-50% (MgF2+CaF2+SrF2+BaF2+PbF2), and 0-25% (LiF+NaF+KF), and 0.5-7 pts.wt. CuO for 100 pts.wt. base glass which contains 0.5-32% F and 26-54% O. The F is introduced in the phosphate glass to enhance the chemical durability and also by controlling the P2O5 content in the prescribed range, the loss of transparency prevented and the molding workability is enhanced.