A portable electronic apparatus and a power management method are disclosed. The portable electronic apparatus comprises a processor and an embedded controller (EC). The EC determines whether the processor starts a throttling mechanism according to a current power consumption, a proportional term, a last power consumption, a lower bound, a delta power and a derivative term. The EC determines whether the processor cancels the throttling mechanism according to the current power consumption, the lower bound, a count that the power consumption is lower than the lower bound, and an integral term.