The user device having an auxiliary power unit

A user equipment according to the invention comprises an auxiliary power unit for at the time of sudden power-off of the main power supply and the main power supply for supplying power to the user equipment, to supply power to the user equipment. Here, the secondary power supply apparatus is characterized in that a mode set according to the power amount. The invention can be used not only to avoid data loss in the power-off by performing the data control, no matter in accordance with the mode setting and the mode setting in accordance with the power supply amount of the super capacitor, the most of the auxiliary power supply.