In a system controller in which a plurality of CPUs connected through a shared bus are connected to a plurality of memory units or IO devices through a bus for separate transfer of a read instruction from a read data return, a CPU which has issued a new instruction and the destination of the instruction, and a CPU which has issued an instruction being suspended and the destination of the instruction are held, the issue order of the return data and the transfer instruction is maintained based on the held contents in a read time, and transfers, which are first serialized and transferred through the shared bus, are issued in parallel using a plurality of connection paths. Thus, the performance of the system controller using a plurality of CPUs can be successfully improved.