G31.9+0.0 (3C 391) is a mixed-morphology supernova remnant (SNR) observed in GeV gamma rays by Fermi Gamma Ray Space Telescope's LAT (Fermi-LAT), as well as in the 0.3−10 keV X-ray band by Suzaku. 3C 391 is located at a distance of 8.5 kpc and maser emission spots show that this SNR is interacting with molecular clouds. In this poster we will present the analysis results of gamma- and X-ray data on 3C 391 taken with Fermi-LAT and Suzaku and will interpret the multi-wavelength spectrum by showing the main emission models.