An energy adjustor coupled between a fuel cell group and a secondary battery group is disclosed. A load is coupled to the secondary battery group in parallel. The energy adjustor includes a boost regulation module, a drop regulation module, a detecting module and a control module. The boost regulation module boosts an output voltage of the fuel cell group to generate a first adjustment voltage according to a first control signal. The drop regulation module drops the first adjustment voltage to generate a second adjustment voltage to the load according to a second control signal. The detecting module detects at least one of the fuel cell group, the boost regulation module, the drop regulation module and the load to generate a detection result. The control module generates the first and the second control signals according to the detection result.