The present invention relates to a wireless USB modem device supporting dual service for portable Internet and digital broadcasting. The wireless USB modem device includes a portable Internet communication module and a digital broadcast reception module. The wireless USB modem device includes a USB hub connected to USB interfaces of both the portable Internet communication module and the digital broadcast reception module, and configured to relay data to a user terminal. A switching mode power supply unit is implemented in a DC-DC switching mode, is supplied with power from the user terminal and is configured to apply power to the portable Internet communication module and the digital broadcast reception module so that the portable Internet communication module and the digital broadcast reception module can be simultaneously driven. Accordingly, a separate control unit for controlling USB interfaces is not required, and the number of peripherals connected to the USB port of the portable user terminal can be reduced. Further, portable Internet service and digital broadcasting service can be simultaneously provided, thus enabling bidirectional digital multimedia broadcasting service and Internet service to be simultaneously supported anytime and anywhere without regard to spatial or temporal restrictions.