To flexibly cope with the case of equally giving a bus using right to any device and the case of giving priority in the acquiring of the bus using right to a specific device by avoiding the delay of a response to the bus using request by the successive inspection of the bus using request in a circulating priority order system.

Plural devices 102a to 102h are connected to one bus 101 to receive a bus using request signal 104 from the devices 102a to 102h. When a bus using request signal 104 is outputted from the plural devices 102a to 102h, a bus arbitration device 103 executing bus arbitration giving the bus using right permitting the access of the bus 101 stores a variable weighting value, which becomes different value at each device 102a to 102h executing a bus using request and varies the value each time of bus arbitration, to arbitrate this variable weighting value as the priority of the bus using right.