PURPOSE: To improve joining precision and reliability so as to efficiently join by applying beam on both surface of an object to be joined, cleaning both surfaces and joining with successively laminating to prevent damage on joining surface irrespective of the number of the object to be joined.

CONSTITUTION: A preparation chamber 6 to accommodate an object to be joined, a cleaning chamber 7 to apply beam and a joining chamber 8 arranged with heating/pressurizing means are successively laid out in adjacent relation, maintaning vacuum atmosphere, an object to be joined is taken out from the preparation chamber 6 one by one by the transfer means 5, with reversing it in the cleaning chamber 7 both surfaces are faced toward an irradiating gun 20, in the joining chamber 8 plural cleaned objects to be joined are successively laminated, subjecting to pressurizing/heating. Accordingly, damage on joiing surface of the object to be joined is not caused, cleaning of joining surface by beam irradiation is executed perfectly and surely, joining precision for plural objects to be joined is improved.