1. An image processing apparatus including a reconfigurable circuit in which functional blocks that perform image processing can be reconfigured, the image processing apparatus comprising: a memory device configured to store in advance configuration data, for each plurality of the functional blocks, for configuring the functional blocks in the reconfigurable circuit; and a CPU coupled to the memory device, wherein the CPU is programmed to function as: a first receiving unit configured to receive a designation of a job to be executed; a first reconfiguration unit configured to read out, from the memory device, necessary configuration data for executing the designated job before receiving a start instruction of the job, and reconfigure the reconfigurable circuit; a second receiving unit configured to receive a setting value designated for executing the designated job; a second reconfiguration unit configured to read out, from the memory device, necessary configuration data for executing the designated job using the designated setting value before receiving a start instruction of the job, and reconfigure the reconfigurable circuit by updating the reconfigurable circuit reconfigured by the first reconfiguration unit; and a job execution unit configured to execute the job by executing a processing using the reconfigurable circuit reconfigured by the second reconfiguration unit when accepting the start instruction of the job.