Abstract: The invention provides a circuit-mounted board which can improve the reliability in the operations of a system having expansion slots. The load adjustment board is a circuit-mounted board to be used by being inserted into the expansion slot of the system, and comprises a plurality of connection pins to obtain electric connection with another board, and devices each having variable electric property, such as a variable resistance or a variable capacitor, provided for each connection pin. One end of each device is connected to the respective connection pin, and the other end is fixed to the predetermined potential (ground, for example). The board is inserted into a vacant slot of the expansion slots of the system to suppress reflection noise etc.