In order to ensure that a normally-off computer connected to a volatile component operates normally and rapidly after operation of turning-on/off of a power supply is executed, a computation processing device which has nonvolatile registers and which is able to continue processing of data retained in the device after the power supply is turned off/on without retracting the data to an external device includes at least: a central processing unit including the nonvolatile registers; a connection unit for a volatile component which saves internal information in a volatile storage element thereof; a nonvolatile storage unit for saving a return program from a power-off state of the volatile component; and an inspection unit notifying that a potential of the power supply in the computation processing device has reached an operation potential at a time of return. The central processing unit loads the return program from the nonvolatile storage unit in response to a notification signal from the inspection unit and executes it.