An optical sensor to be used for gas pressure detection is described. The device is based on the spectral response associated with the surface plasmon resonance (SPR) occurring on a 50-nm gold surface. The operation of the device relies on the fact that the refractive index of a gas changes with pressure, which leads to a shift in the resonance wavelength dip in the SPR curve. Experiments performed on nitrogen gas at room temperature demonstrated the sensor resolution of RUI, which corresponds to a pressure resolution of . The new device offers the benefits of wide dynamic range, no moving parts, and possibly 2-D imaging of pressure distribution. Further development of the device may lead to a new type of optical pressure sensors.