Disclosed herein is a battery pack which includes a plurality of battery modules housed in a housing. The battery modules are connected in series to each other via connecting members that connects external terminals of the battery modules to each other. The battery modules are classified into groups, each being comprised of at least two of the battery modules, two terminal ones of which have a potential difference of at most V or less between themselves. A first connecting member connects the external terminals of the battery modules to each other between two adjacent ones of the groups. A second connecting member connects the external terminals of the battery modules to each other within an identical one of the groups. If water penetrates into the housing, the first connecting member is electrically cut off, preferentially relative to the second connecting member.