To improve reliability of a soldered part by releasing a stress.

In an electronic part 2 mounted on a surface of a printed board 1, an electrode 2b is pulled out on the surface of a ceramic board 2a of a mother board. Also, an insulator part 3 is integrally provided on the surface of the printed board 1 side in the ceramic board 2a. This insulator 3 is provided so as to be projected from the surface of an electrode 2b faced to a wiring pattern 1b of the printed board 1 only by prescribed dimension 50-100 μm. This electronic part 2 is arranged at the prescribed position of the surface of the printed board 1, while the face on which the insulator part 3 is formed is faced to the print board 1 side, and this electronic part 2 is soldered in a state that a clearance equivalent to the height of the insulator part 3 is secured between a wiring pattern 1b of the print board 1 and the electrode 2b of the electronic part 2 by the insulator part 3.