A bus control circuit configured to transfer access commands for performing exclusive access between a first bus specification and a second bus specification by converting from a first exclusive access command applying to the first bus specification which deals with exclusive access, into a second exclusive access command of the second bus specification which doesn't deal with the exclusive access. The circuit includes an exclusive access command conversion circuit for receiving the first exclusive access command, converting the first exclusive access command into the second exclusive access command, and outputting the second exclusive access command; an exclusive access command generation circuit for receiving the second exclusive access command and generate the first exclusive access command; an exclusive access response issuing circuit for issuing exclusive access response information for the second exclusive access command; and an exclusive access response receiving circuit for receiving exclusive access response information for the second exclusive access command.