A current detection surface plasmon resonance (SPR) sensor with an Au grating on an n-Si wafer was proposed. SPR excitation light is illuminated from the backside of the device and diffracted by the grating. Since the diffraction provides matching conditions, SPR can be coupled to the Au/analyte interface. Since the coupled SPR excites free electrons on the Au surface, the SPR can be detected as a current signal by a Schottky barrier diode formed on the Au/n-Si interface. The obtained angular current spectrum showed clear agreement with SPR coupling theory, thereby confirming that the sample on the Au surface can be electrically detected using the proposed sensor. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement