PURPOSE: To prevent the damage of components due to their contact with the outside by providing a channel for housing mounting components.

CONSTITUTION: A channel 4 is provided on a test board body 1, the inside face of the channel 4 is made a conductive face and a component 3 such as a chip capacitor are sandwiched between the conductive face 5 and a through hole 2 to attach by soldering. Therefore the conductive face 5 of the side face of the channel 4 is connected with the through hole 2 to use as part of wiring and the component 3 can be mounted without being projected on the surface of the test board body 1. Thereby the damage of the component by coming in contact with the outside is eliminated and reliability is high to be functional.