Battery monitoring device, resistance value deriving method, and cell voltage deriving method

The invention provides a battery monitoring device, a resistance value deriving method and a cell voltage deriving method. The resistance value of a resistance element arranged between a battery cell and a cell selection switch can be measured. The battery monitoring device includes: an analog-to-digital converter; and a plurality of cell selection switches selectively connecting any one of the plurality of battery cells to the analog-to-digital converter. Each of the cell selection switches has: a first switch unit that is provided on a conductive path from one of the plurality of battery cells to the analog-to-digital converter, and that sets the conductive path to a conductive state in an ON state and to a non-conductive state in an OFF state; a second switching unit that switches on/off of the first switching unit; a third switch unit that switches the magnitude of the current flowing into the first switch unit when the first switch unit is in the ON state; and a resistive element disposed on the conducti