To provide an electronic apparatus and electronic apparatus manufacturing method enabling selection of a necessary functional block from among multiple functional blocks or units so that numerous functions can be selectively used with few input/output terminals. An electronic apparatus has input/output terminals 101 for connecting to an external circuit; functional blocks or units 101a to 102c such as DRAM, flash ROM, and an ASIC; a switching circuit 103 that is a two-way analog switch for switching between the functional blocks or units 102a to 102c and input/output terminals 101; and function selection terminals 104 for applying to the switching circuit 103 a signal indicating which functional block of functional blocks or units 102a to 102c to connect to the input/output terminals 101. Because the necessary functional block and the input/output terminals 101 can be connected according to the input to the function selection terminal 104, numerous functions can be selectively used with only a few input/output terminals.