To provide a central processing unit(CPU) capable of effectively executing speculative processing while furthermore reducing the storage quantity of information, the quantity of hardware or throughput.

The CPU provided with plural operation execution units 8 to 11 and capable of allocating respective units 8 to 11 in the case of executing an interpreted instruction is also provided with a group value generation part 6 for providing a group value for identifying which instruction group obtained by dividing an instruction string of a program by a specific instruction includes an instruction concerned to the instruction at the time of executing it, speculation judging parts 12 to 15 for judging whether the execution of an instruction is speculative or not by using the group value applied to the instruction and a register retreating part 16 for storing information for restoring a register updated by a speculatively executed instruction to a state held before the execution of the instruction.