PURPOSE: To produce a non-magnetic substrate dense and small in crystal grain diameter at a low sintering temperature.

CONSTITUTION: In the producing method of non-magnetic ceramic substrate by adding Al portion to CoO and NiO or NiO of a basic composition, a part or all of the Al portion is added in such a state that γ, η, κ, χ, δ or θ phase or amorphous Al2O3, or aluminum hydroxide, alumina hydrate is alone or plurally mixed with each other, and then the sintering is executed. As a result, the magnetic head use non-magnetic substrate dense and having fine and uniform crystal grain diameter is obtained.