Electric storage device protection apparatus, electric storage apparatus, starter battery, and method of protecting electric storage device

Heating of the rectifier component is less likely to occur and an electric storage device is less likely to be in an overcharge state or an overdischarge state. At least a first switch (12A) becomes in a closed state when an assembled battery (11) is not in an overcharge state. A diode (D) is not connected in series to the first switch (12A) and therefore, heating of the diode (D) is less likely to occur compared to a configuration in which the diode (D) is connected in series to the first switch (12A). A BMS (13) makes the first switch (12A) to be in an open state and a second switch (12B) to be in a closed state when the assembled battery (11) is close to the overcharge state. Accordingly, a current flow flowing through the assembled battery (11) is interrupted by the diode (D) and this prevents the assembled battery (11) from being in the overcharge state.