A glass paste containing pigment particles of silicon tetraboride each covered with a silica glass film (silica glass layer) having a silicon dioxide content higher than that of the glass structure present at the interface with the pigment particle and a predetermined thickness. In the glass film formed by applying this glass paste to the surface of a substrate and firing it, a silica glass film (silica glass layer) which is relatively lowered in the reactivity with the pigment particle by virtue of its silicon dioxide content higher than that of the glass structure is formed at the interface between each pigment particle and the glass structure. The use of the glass paste effectively prevents a high-radiation glass film wherein a high-radiation pigment is dispersed in a glass structure from undergoing interfacial reactions between the pigment and the glass structure during production and use thereof.