NOVELTY - The method involves forming adherend materials (41,42) by forming plasma polymerization films (3) containing electroconductive component on respective base materials (21,23). The adherend materials are made to contact each other to form a temporary joined structure (5). The UV-rays having wavelength of about 150-300 nm are irradiated onto the plasma polymerization film and electric field is applied onto the plasma polymerization film to form a permanent joined structure (1).    USE - Method for joining base materials in manufacture of wiring board (claimed). Can also be used in manufacture of transistor, diode, semiconductor memory, quartz oscillator, reflective mirror, micro mirror solar cell, inkjet print head, pressure sensor, acceleration sensor, LCD element, electroluminescent element, electrophoretic display element, fuel cell, recording medium e.g. magnetic recording medium, magneto optical recording medium, etc.    ADVANTAGE - The base materials can be joined firmly at low temperature and a reliable wiring board with excellent dimensional accuracy can be manufactured easily by using simple technique.    DETAILED DESCRIPTION - The method involves forming plasma polymerization films containing same materials on respective base materials (21,23) to form adherend materials after performing plasma processing. The base materials have different rigidities. The average thickness of the plasma polymerization film is 1-1000 nm. Hydroxyl group exists in the plasma polymerization film formed on oxide film of the base material (23). The adherend materials are made to contact each other and temporary joined structure is formed. The base materials are joined permanently by heating and by applying compressive force of about 0.2-10 MPa. The heating temperature is 25-100 degrees C. An INDEPENDENT CLAIM is included for the joined structure which comprises two base materials. The joining strength of the base materials is 5 Mpa or more. The resistivity of the plasma polymerization film is 1asterisk10-3 ohm-cm or less.    DESCRIPTION OF DRAWING(S) - The drawing shows a longitudinal cross-sectional view explaining joining of the base materials. (Drawing includes non-English language text)    Joined structure (1)    Plasma polymerization film (3)    Temporary joined structure (5)    Base materials (21,23)    Adherend materials (41,42)