The data sharing apparatus in the present invention includes a first processor 10 and a second processor 20, each of a different endianness, that are both connected to the memory via the data bus, in a byte order based on the endianness of the first processor 10. It also includes an address conversion unit 21 which converts at least one lower bit of an address to indicate a reversed position of data in the data bus, and outputs the converted address to the memory, in the case where the second processor 20 performs a memory access on the shared memory for data with a smaller width than the data bus.