To provide a semiconductor device having a nonvolatile memory improved in characteristics. In the semiconductor device, a nonvolatile memory has a high-k insulating film (high dielectric constant film) between a control gate electrode portion and a memory gate electrode portion and a transistor of a peripheral circuit region has a high-k/metal configuration. The high-k insulating film arranged between the control gate electrode portion and the memory gate electrode portion relaxes an electric field intensity at the end portion (corner portion) of the memory gate electrode portion on the side of the control gate electrode portion. This results in reduction in uneven distribution of charges in a charge accumulation portion (silicon nitride film) and improvement in erase accuracy.