Provided is an energy storage device state estimation device (100) for estimating a state of an energy storage device (200), the energy storage device state estimation device (100) including: a temperature estimation part (110) configured to estimate a temperature of the energy storage device (200); and a state estimation part (120) configured to estimate a state of the energy storage device (200) using the temperature of the energy storage device (200), wherein the temperature estimation part (110) is configured such that the energy storage device (200) is divided into a plurality of regions, the respective regions are set as internal regions, a region outside the energy storage device (200) adjacently disposed to the internal region is set as an external region, and a temperature of the energy storage device (200) is estimated using an internal heat transfer amount which is a transfer amount of heat between the two internal regions disposed adjacently to each other and an external heat transfer amount which is a transfer amount of heat between the internal region and the external region disposed adjacently to each other.