In a semiconductor device using a nonvolatile memory, high speed erasing operation and low power consumption are realized. In a nonvolatile memory in which a channel formation region, a tunnel insulating film, and a floating gate are stacked in this order, the channel formation region is formed using an oxide semiconductor layer. In addition, a metal wiring for erasing is provided in a lower side of the channel formation region so as to face the floating gate. With the above structure, when erasing operation is performed, charge accumulated in the floating gate is extracted to the metal wiring through the channel formation region. Consequently, high speed erasing operation and low power consumption of the semiconductor device can be realized.