To provide a method by which a dielectric line can be manufactured efficiently with high reliability and accuracy.
After a resist material 22 is formed on a green molded body 23 and through holes 8 and 9 for through conductors are formed through the molded body 23, an unburned dielectric substrate 2a is obtained by removing a prescribed portion of the molded body 23 by sandblasting in an eroding step by using the resist material 22 as a mask. At the same time, the marginal sections 12 of the opened ends of the through holes 8 and 9 and internal peripheral surfaces 13 of the holes 8 and 9 are smoothed, Subsequently, a dielectric substrate 2 having a raised section 3 and wing sections 4 and 5 respectively having the through holes 8 and 9 is obtained by performing a burning step. Thereafter, conductive films are formed on both surfaces of the substrate 2 and, at the same time, through conductors are formed in the through holes 8 and 9 so as to electrically connect the conductive films formed on both surfaces of the substrate 2 to each other.