A battery pack structure includes a chamber, a cooling duct arranged outside the pack case, and a connector that communicates the chamber and the cooling duct with each other. The connector includes a first opening, which is connected with the chamber in a state of being sealed by a first sealing member, a second opening, which is connected with a cooling duct in a state of being sealed by a second sealing member, a first sealing surface, which is formed in a peripheral part of the first opening and is either a tube-shaped surface or a plane that faces a chamber inlet surface though the first sealing member, and a second sealing surface, which is formed in a peripheral part of the second opening and is a tube-shaped surface or a plane that faces a duct outlet surface through the second sealing member.