NOVELTY - A joining film (a) (31) of metal atom (i), a metal atom (ii), and a leaving group-containing organic component is formed on a base material (b1) (11). A joining film (b) (32) is formed on a base material (b2) (12). The joining film (a) and joining film (b) exhibits adhesiveness by providing energy, and the leaving group which exist in the surface vicinity of the joining film (a) and joining film (b) are detached. The base material (b1) with joining film (a) and base material (b2) with joining film (b) are bonded together to obtain a joined component (5).    USE - Method used for joining to-be-joined component (claimed). Uses include but are not limited to transistor, diode, piezoelectric element, optical lens, optical filter, pressure sensor, magneto-optical recording medium, organic electroluminescent element, solar cell and micro reactor.    ADVANTAGE - The method provides joined component having excellent dimensional accuracy and joint strength efficiently, at low temperature. The joining film in the joined component has excellent weather resistance and chemical resistance. The generation of peeling and curvature in the joined component is suppressed.    DETAILED DESCRIPTION - A joining film (a) containing a metal atom (i), a metal atom (ii) with ionization tendency more than the metal atom (i), and a leaving group-containing organic component is formed on a base material (b1). A joining film (b) containing metal atom (i), metal atom (ii) and leaving group is formed on a base material (b2). The joining film (a) and joining film (b) exhibits adhesiveness by providing energy to joining film (a) and joining film (b), and the leaving group which exist in the surface vicinity of the joining film (a) and joining film (b) are detached from the joining films (a,b). The base material (b1) with joining film (a) and base material (b2) with joining film (b) are bonded together by adhering joining film (a) and joining film (b) to obtain a joined component.    DESCRIPTION OF DRAWING(S) - The drawings show the cross-sectional view of the joining method. (Drawing includes non-English language text)    Joined component (5)    Base materials (11,12)    Substrates (21,22)    Joining films (31,32)    Surfaces (351,352)