Copyright © Materials Research Society 2018. A transmission surface plasmon resonance image (TSPRi) obtained with a plasmonic grating structure was investigated in combination with a smartphone camera. A substrate of a gold-coated CYTOP grating/glass slide showed the TSPR excitation wavelength of 675 nm at the incident light angle of 30°. The TSPRi acquired from a smartphone camera assembled with liquid crystal tunable filters corresponded with spectroscopic results. The sensitivity of this technique was 282/RIU. Due to changes in the sensitivity of the TSPRi intensity to the refractive index of the environment, this technique can be further developed for portable devices for sensor applications.