PURPOSE: To match the coeffts. of expansion of a slider and core block by incorporating specific ratios of at least SiO2, PbO, B2O3, Al2O3 and Bi2O3 into titled glass.

CONSTITUTION: SiO2 is incorporated at least at 13W16wt% into the glass for sealing a magnetic head, PbO at 66W70wt%, B2O3 at 2W5wt%, Al2O3 at 1W6wt% and Bi2O3 at 8W12wt%. This glass for sealing has 93W100×10-7/°C coeffts. of thermal expansion in a 100W300°C range and can match the coeffts. of thermal expansion of the slider consisting of ceramics and the core block consisting of ferrite. Said glass can join and seal the slider and core block extremely satisfactorily without cracking. The excellent resistance to weather and wear is thus obtd. and the magnetic head having high durability is obtd.