The present invention provides a secondary battery in which effective utilization of the installation space for a pressure sensitive sensor and a heater is more sufficiently achieved and high rate deterioration and electrolytic solution deterioration can be more sufficiently detected. The present invention relates to a secondary battery including: one or more battery cells; a case for housing the battery cells; and a heater provided between a battery cell in contact with the case and the case and/or between two battery cells adjacent to each other among the battery cells, in which the heater serves as a pressure sensitive sensor that detects a pressure distribution between the battery cell in contact with the case and the case and/or between the two battery cells adjacent to each other.