Methods for evaluating battery safety under internal short-circuit conditions are improved to eliminate variations in evaluation results and accurately evaluate battery safety under internal short-circuit conditions. An internal short-circuit is caused in a battery by using an internal short-circuit causing method in which battery information obtained upon the occurrence of an internal short-circuit hardly changes with the structure of the battery. At this time, the battery information is detected to accurately evaluate the safety of the battery upon the internal short-circuit and identify the safety level.