A battery monitoring device monitors a battery that is rechargeable and dischargeable. The battery monitoring device includes a factor monitoring unit that monitors a factor that leads to an abnormal heat generation phenomenon in which a temperature of the battery continues to rise unintentionally, and an abnormality detection unit that detects an abnormality in the battery. The abnormality detection unit reduces occurrence of the abnormal heat generation phenomenon in advance based on a monitoring result of the factor, and detects an abnormal state occurring in the battery at an initial stage of the occurrence of the abnormal heat generation phenomenon to implement a countermeasure against the abnormal heat generation phenomenon based on a detection result of the abnormal state.