To perform a context switch method according to the type of a program.

When a process that is currently executed by an arithmetic processing unit is switched, attribute information indicating the use frequency of a register out of a plurality of registers used by a process which the arithmetic processing unit is going to execute next is read out from a memory, and when the use frequency of the register indicated by the attribute information is larger than the predetermined frequency, the value of the register to be used by a process which the arithmetic processing unit is going to execute next is saved in a main memory, owner information indicating a process that is using the register to be used by the process which the arithmetic processing unit is going to execute next is read out from the memory, and the value of the register saved in the main memory is restored to the register when the owner information indicates a process other than the process to be executed next.