Abstract: A data interface for communicating data between processors having: a writing-side register group in which data in a writing-side processor which transmits data is written in response to a clock signal; a reading-side register group into which the data written into the writing-side register group is transferred and written in response to a later clock operation, the data being read out by a reading-side processor of a data receiving side; a write controller for selectively writing data in a register in the writing-side register group in accordance with an address signal and a write signal of the writing-side processor; and a read controller for selectively reading data from a register in the reading-side register group in accordance with an address signal of the reading-side processor; so that a double buffer structure consisting of the writing-side buffers and the reading-side buffers causes the address signal and the data signal to individually be connected in the writing side and the reading side.