To provide an image processing apparatus which can realize a plurality of external interface functions at a low cost.

There are set an ASIC 8 for input/output connected to an I/O bus 7 fitted for input/output of signals to an external device, and a sub-substrate 10 (20) which has a connector corresponding to an interface to the external device and is connected to the external device. The ASIC 8 for input/output has an input/output terminal connected to the sub-substrate 10 (20) and is configured to input/output signals conformed to a plurality of interfaces by the same input/output terminal. Since inputting/outputting of signals conformed to the plurality of interfaces is carried out by the same input/output terminal of the ASIC 8 for input/output, various interfaces can be realized by setting the sub-substrate conformed to the interface desired to be used.