BUS TRANSMISSION SYSTEM

PURPOSE:To provide the bus transmission system which enables direct data transmission between bus controlled parts connected to an in-device bus and improves the use efficiency of the bus as to a communication device which has the in-device bus. CONSTITUTION:A bus control part 1090 and plural bus controlled parts 110 and 120 are provided, and the bus control part 100 and bus controlled parts 110 and 120 are connected by a signal bus 130, a time slot position signal line 140, and a transmission mode control signal line 1509 which transmits a transmission mode control signal; and the transmission mode control signal is used to indicate data transmission between the bus control part 1009 and bus controlled part 110 or 120 or data transmission between the bus controlled parts 1109 and 120, and for the data transmission between the bus controlled parts, the bus control part 100 sends relative information to only the relative bus controlled parts 110 and 120, so that the data transmission is performed only between the directly relating bus controlled parts 110 and 120.