ESTIMATION DEVICE

An estimation device configured to estimate a charge rate of a battery includes a voltage sensor configured to detect a voltage of the battery, a temperature sensor configured to detect a temperature of the battery, and a processing circuit. The processing circuit is connected to the voltage sensor and the temperature sensor and is configured to execute, while a vehicle is parked, an estimation process of estimating the charge rate of the battery based on a detection voltage and a detection temperature. The detection voltage is detected by the voltage sensor. The detection temperature is detected by the temperature sensor.