To improve the operability of an electronic device having small operation keys with a narrow space between the operation keys.

A code analysis section 21 acquires operation key information, which indicates an operated operation key 15 or 28, from a remote controller 100 or a projector 200. A code execution determination section 22 acquires the operation key information from the code analysis section 21, and determines whether the operation key 15 or 28 according to the operation key information is usable in a present operation mode. When the operation key 15 or 28 is not usable based on the determination result by the code execution determination section 22, an operation processing section 23 determines whether the operated operation key 15 or 28 is kept depressed for long time. When the operation processing section 23 determines that the key is kept depressed for long time, it executes the processing corresponding to the operation key 15 or 28 that is determined to be not usable.