A battery pack cooling mechanism for a hybrid vehicle is provided. An opening is formed in a floor panel located rearwardly of the vehicle. An upper portion of a battery pack inserted into the opening is closed by a cover panel. The opening is formed in misalignment with above an exhaust pipe so that the battery pack is arranged adjacent the exhaust pipe in the width-wise direction of the vehicle. An air-intake device is mounted on a top surface of the battery pack. An air outlet port of the air-intake device opens frontward of the vehicle. An air outlet port of an air outlet duct opens more rearwardly than the battery pack. A filer element which removes foreign substances is disposed in the air-intake device. A service lid is disposed on an upper portion of the cover panel for maintenance of the filter element.