A power management system for supplying generated power from a solar cell, which is the power generator, to a power grid and a storage battery, which is the power storage device, includes a controller that controls charging power supplied to the storage battery and output power from the solar cell in order for the generated power not to flow backward to the power grid; a voltage monitoring unit that monitors the voltage of the power grid; and a current monitoring unit that monitors the current from the power grid. The controller controls the charging power sent to the storage battery in accordance with power purchased from the power grid on the basis of the voltage and the current; and the storage battery and the solar cell are controlled in accordance with different thresholds of purchased power.