An estimation device includes an acquisition unit that acquires current, voltage, and temperature of a lead-acid battery, a data accumulation unit that accumulates an integrated value or a calculated value of the current, voltage, and temperature that are acquired, an identification unit that identifies specific gravity of an electrolyte solution of the lead-acid battery based on history data accumulated in the data accumulation unit, an estimation unit that estimates a freezing risk of the lead-acid battery based on identified specific gravity of an electrolyte solution, and an output unit that outputs an estimation result of the estimation unit.