A semiconductor device includes a central processing unit and a processor on one semiconductor substrate. The processor includes a buffer for storing a register setting list and notifies the central processing unit of an access complete signal indicating completion of reading the register setting list. The central processing unit changes the register setting list within a memory based on the access complete signal and notifies the processor of an update request signal. The processor reads the register setting list changed by the central processing unit into the buffer based on the update request information.