The area between the Clarion and Clipperton fracture zones (NE equatorial Pacific) is one of the highest manganese nodule abundance in the world oceans. A detailed analysis of MR1 sonar images and free-fall grab (FFG) data with subbottom profiles in the area reveals a close relationship between sonar characters of seafloor and manganese nodule occurrence. Eight sonar facies are identified on the basis of back-scattered intensity, distribution pattern and texture. These sonar facies can be interpreted as (1) volcanic seamounts (facies I-1), (2) faults bounding abyssal hills (facies I-2 and II-1), (3) lava flows or mass-flow deposits around volcanic seamounts (facies I-3 and II-2), (4) crests of abyssal hills (facies II-1), (5) troughs between abyssal hills (facies III-1) or flat area (facies III-2) with relatively thick sediments, and (6) flat area covered with thin sediments (facies II-3). In the area consisting dominantly of facies II-1 and II-3, manganese nodules occur abundantly. In contrast, zones consisting of facies I-1, I-2, I-3, II-2, III-1 and III-3 are characterized by low abundance of manganese nodules.