In this study, to clarify the distribution of gas-hydrate and its formative environment of seabed methane, and to evaluate the potential as resource of gas-hydrate, the geologic surveys were conducted by NT13-20 and OS263 cruises covering a wide area of Abashiri and Shari Submarine Canyons in the Okhotsk Sea. The conducted investigations are the seismic geologic survey, the bathymetry and the gas-flare observation by an echo sounder, and core sampling of sea-bottom sediments. Moreover, to examine the soil properties of sea bottom sediments, some kinds of shipboard tests such as handy vane shear and cone penetration tests, and physical properties tests such as water content and grain size distribution tests, were performed for the samples.