NOVELTY - The device has a semiconductor integrated circuit unit whose output is transmitted by a corresponded capacitor to the semiconductor integrated circuit unit on an upstream side of the daisy chain connection using a two-wire transmission path. Wire length of a wiring part connecting the capacitor with a corresponding internal connection terminal on a wiring board, is configured to include a length as to hinder resonance from being caused against electromagnetic wave noises in an electromagnetic wave noise environment under which the wiring board is arranged.    USE - Charging/discharging monitoring device for monitoring charging/discharging of a battery pack used for driving a motor of an electric vehicle (EV) or a hybrid electric vehicle (HEV) combined with a petrol engine.    ADVANTAGE - The two-wire transmission path configures the transmission path provided between a data transmission circuit of a monitoring integrated circuit and a data reception circuit of the monitoring integrated circuit configured as follows in order to prevent the influence of the exogenous electromagnetic wave noises and achieve the extension of the transmission distance to exclude the influence to/from the communication counterpart in direct current (DC), achieve charge voltage data of the battery cell at high quality to a microcontroller unit by preventing the influence of the exogenous electromagnetic wave noises, thus achieving the accurate charging/discharging control operation with the actual condition of a battery cell.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a battery pack    (2) a monitoring device for a battery system.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic block diagram of a battery pack to which a charging/discharging monitoring device is applied.    Clock reception circuit (CR1)    Clock transmission circuit (CT1)    Monitoring integrated circuit (IC2)    Secondary battery module (MD2)    Upstream-side secondary battery module (MD3)