A processing load of a high performance application processing such as a voice, an image and the like is reduced, and a processing capacity of a base band processing is improved. A semiconductor integrated circuit device used in a mobile communication system such as a cellular phone is provided with a base band CPU block performing a base band processing for executing a base band protocol stack, an application system CPU block executing a high-level OS and controlling applications other than the base band processing, an application real-time CPU block executing a real-time OS and the like and controlling an image/voice processing, all of which are formed on one semiconductor chip. Further, internal high-speed buses to which these CPU blocks are connected are respectively connected via bridges.