There is provided a highly reliable storage battery apparatus which can diagnose the status of a temperature detection unit and a cooling unit. In the storage battery apparatus comprising a battery module including one or more batteries, a plurality of temperature detection units and a cooling unit cooling the battery module, the temperature detection units measure, at least, the temperature of the cooling medium inputted to the storage battery apparatus, the temperature of the cooling medium outputted from the storage battery apparatus, and the temperature of at least one of the batteries and the battery module.