Submarine hydrothermal polymetallic sulfides are present in the sea near Izu- Ogasawara and Okinawa in Japan. These sulfide deposits are primarily composed of iron, barium, zinc, and lead, and include copper, silver, and gold. Though clearly identifiable as polymetallic sulfides, their mineral processing behavior is known to be totally different from that of the Kuroko deposits extracted from land mines in Japan. In this report, a selection of ore samples of submarine hydrothermal polymetallic sulfides from around Japan were analyzed, and the typical characteristics influencing mineral processing were investigated. The characteristics of the existing mineral phases, such as the mineral components, mineral domain size, and element distribution on ground sample, were especially focused on and investigated in the study, with respect to the grinding size required to achieve sufficient mineral liberation to conduct effective mineral processing. The results suggest that many types of sulfide deposits are present even in highly limited deposit regions, so that the respective samples are difficult to treat as one group with respect to mineral processing, because the mineral components, domain size, and trace elements co-existing within the minerals differ among the samples.