A power management device of electronic card includes a functional module, an interface bus, a bus bridge unit, a power storage unit, an external power input unit and a power control unit. The power control unit controls the bus bridge unit, the external power input unit, and the power storage unit, so as to supply the interface power from the bus interface unit to the functional module and further charge the power storage unit, directly supply the interface power from the bus interface unit to the power storage unit for charging the same, supply the external power from the external power input unit to the functional module and further charge the power storage unit, or directly supply the external power from the external power input unit to the power storage unit for charging the same.