PURPOSE: To perform a test in ventilation state by providing a positioning means of a wiring board on one end of a ventilation flue, providing a shielding means, etc. on the other end side of the ventilation flue, positioning exactly the wiring board to be texted, whose size is different, and also shielding the ventilation flue from the outside.

CONSTITUTION: In case of setting a wiring board of the largest size to be tested to a ventilation flue 14, it is set so that a gap between said flue and the board 7 is not made even in a state that a shielding means 15 has been reduced. Also, in case when the size of the board 7 is small, the means 15 is expanded until it abuts on the board 7. In this case, a positioning means 62 is also expanded together with the means 15, therefore, the other end of the board 7 can be positioned and fixed at a prescribed position by the means 62. In this state, when air is fed from one duct 16 and air is exhausted from the other duct 17, cold air and hot air, etc. can pass efficiently through the ventilation flue 14 under the board 7. In this way, the means 15 expands and contracts in accordance with the size of the board 7, the means 62 can be moved to a position corresponding to a size of the board 7, and also by expanding it to a position where it abuts on the board 7, the board can be enclosed so that air in the ventilation does not escape to the outside.