To provide an image processor in which power consumption can be suppressed as compared with prior art by processing a job received from an external unit through a communication means, and obtaining or altering the state of the processor while suppressing the frequency of releasing power saving state as much as possible.

When a job is received from an external unit through an NIC 5 during sleep mode, the NIC 5 stores that job temporarily as a suspension job. When predetermined execution start conditions are satisfied, conduction to sub-power supplies 221-229 is controlled and the suspension job is executed by switching a required functional block from "nonconduction state" to "conduction state". Furthermore, instantaneous processing of the suspension job is performed by starting a required functional block of transmission of information about the suspension job, or deletion of the suspension job depending on a request from the external unit during sleep mode.

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