A chargeable battery abnormality detection apparatus configured to detect an abnormality of a chargeable battery includes a processor; and a memory storing instructions executable by the processor, wherein the processor performs the following when executing instructions: calculating a value of an internal resistance of the chargeable battery; determining whether the chargeable battery is being charged or being discharged; determining that an abnormality has occurred in the chargeable battery if either one of the following occurs: the calculated value of the internal resistance decreases while the chargeable battery is being discharged; and the calculated value of the internal resistance increases while the chargeable battery is being charged; and outputting a determination result of the abnormality.