The coal petrological investigation has been carried out on a lump of coal which was collected by a trawl-net from the bottom of the East China Sea at the depth of 90m, from latitude 30°40' 1”N by longitude 126°49' 1”E to latitude 30°30' 4”N by longitude 126°40' 3”E. The mean maximum reflectance of telocollinite maceral in coal is 0.86% in oil. The reflectance and the data on the proximate and ultimate analyses of the lump of coal indicate that the coal is a high volatile bituminous coking coal in rank, comparable to the Takashima coal in western Kyushu, with a low sulphur content. The maceral analyses on 21 coal samples display that the lump of coal contains the content of 42.0 to 86.6% vitrinite, 4.2 to 21.5% liptinite and 2.6 to 47.2% inertinite. Such a high content of inertinite has not been known in Japanese coals. It can be said that the enrichment of inertinite in the lump of coal is a characteristic feature worthy of special mention. The relationships between the coal rank (C%) and some chemical parameters (volatile matter, calorific value, and the H/C atomic ratio) are plotted outside of the general trend of Japanese coal series. Many tubes of organism Serpulidae and Spirorbidae adhere to the surface of a lump of coal. The corners of a lump of coal are rounded in general, and the cutting surface owing to the ripping from the outcrop of the sea bottom can not be observed. Judging from these features, it is presumed that the lump of coal sample was not ripped off from the outcrop of the sea bottom, but was a float. The problem of the provenance of a lump of coal has been left unsolved.