To improve the joint strength of a mounted electronic circuit component mounted on a circuit board to the circuit board.

Since a dummy conductive pad 6 which is joined to a substrate is provided at the center of the mounted surface of the electronic circuit component 1 and joined to the circuit board by reflow-soldering etc., similarly to terminal pads 4, the component 1 is mechanically held on the circuit board when the terminal pads 4 are connected to the periphery edge of the circuit board and, even at the center of the circuit board, the component 1 is held by the dummy conductive pad 6. Consequently, the impact resistance of the component 1 is improved and the peeling of the component 1 from the circuit board is suppressed, because the retention strength of the component 1 is increased as a whole.