PURPOSE: To enable circuit boards to be joined together high in reliability by a method wherein one of the circuit boards is fixed to the pad of a thermocompression bonding device, the other circuit board is placed on the former as it is aligned with the circuit terminal of the former, the end of the mounted circuit board is heated from the rear to tentatively fix the circuit boards together, and then the circuit boards are bonded together through thermocompression.

CONSTITUTION: A glass board provided with an indium tin oxide thin film is set on the pad 9 of a thermocompression bonding device, an anisotropic conductive film 2 is placed on a joining part and tentatively pressure-joined, whereby the film 2 is brought into close contact with the glass board. Then, a carrier film 8 is peeled off from the anisotropic conductive film 2, a flexible board is aligned with the circuit terminals 3 and 3' of the glass board, the flexible board is tentatively fixed to the glass board taking advantage of the tack of the anisotropic conductive film 2, a soldering iron is made to bear against the ends of the circuit boards 1 and 1' from the rear side to bring them into close contact with each other. In this state, a heating head 4 is made to descend, and three flexible boards are pressure-joined together.