The present invention is to provide a bus arbitration apparatus and a bus
arbitration method not reducing data transfer capability as a whole and
preventing a loss of transferred data. It performs the arbitration with
priority in response to properties of bus masters. It sequentially
arbitrates a first hierarchy bus master of which requests are urgent, a
second hierarchy bus master that requests data processing in real time,
and a third hierarchy bus master that is neither a first hierarchy bus
master nor a second hierarchy bus master sequentially.