To provide titania-silica glass which is transparent glass of low thermal expansion, in particular, is of a low thermal expansion coefficient over a wide range of temperatures of 0 to 100.degree. C. (an operating temperature range) when it is used as a photomask or a mirror material in extreme ultraviolet ray lithography, and which is excellent in homogeneity within the field and stability.Titania-silica glass is used which has 8 to 10% by weight of titania and 90 to 92% by weight of silica, where a Ti.sup.3+ concentration is 10 to 60 ppm by weight.