Abstract: A battery monitoring device includes multiple A/D converters, a digital filter, an anti-alias filter, and a detection controller. The multiple A/D converters are provided in correspondence with multiple battery cells in an assemble battery. Each of the A/D converters is configured to receive an input voltage according to a voltage of corresponding one of the battery cells. The digital filter is configured to receive a digital signal output from each of the A/D converters and function as a low-pass filter. The anti-alias filter is configured to suppress aliasing by the digital filter. The detection controller is configured to control operation of the A/D converters so that the input voltage input to each of the A/D converters is A/D converted at a same timing, and detect the voltage of each of the battery cells based on an output signal of the digital filter.