To obviate the occurrence of a thermal influence on members to be joined and to obtain desired joint strength with simple equipment by arranging water and liquid of alcohols, amines, etc., and components which reacts with each other when the liquid attains the prescribed critical point or blow between the metals to be joined to each other or between the metal and ceramics.

The fine powder of metal aluminum is added to the fine powder of aluminum nitride and ammonium alginate and carbonic acid ester are added as a dispersant to the fine powder of aluminum nitride and further, an acrylic emulsion is added to the mixture which is then mixed. Further, the moisture of the mixed joining material is adjusted and thereafter, the joining material is thinly applied on the side of the aluminum nitride sheet to be placed with copper foil. The copper foil is placed thereon and a weight is arranged thereon. Such laminate is rested at room temp. and after lapse of the prescribed time, heat generation begins and immediately an exothermic reaction occurs. When the weight is removed after lapse of one hour, the good joining state is obtd.