Disclosed herein is a Wireless Broadband (WiBro) Universal Serial Bus (USB) modem device having a storage device and a WiBro communication device. A USB hub is connected to the USB interface of the WiBro communication device and the USB interface of the storage device, and configured to relay data to a user terminal through a USB connector. A switching mode power supply unit is configured to have a DC-DC switching mode, receive power from the user terminal, and apply the power by performing high-speed switching so that the WiBro communication device and the storage device are simultaneously driven. The switching mode power supply unit includes a dual output switching mode power supply unit and a single output switching mode power supply unit.