1) There are many methods of representing the dominance by index or percentage. It is difficult to measure the dominance exactly in some grasslands by comparing those indices. 2) Hence the author attempted to represent the real dominance by using the summed dominance ratio of NUMATA(1957)to which the weight factor was added. Namely, the real dominance in a plant community is expressed-by the following formula : (F'+D'+C')/3×w' or(F'+D'+C'+H')/4×w' in which F', D', C', H' and w' are relative values of the frequency, density, coverage, height and weight, respectively, if those values of the Ist rank species are indicated as 100. 3) To compare(F'+D'+C')/3×w' with(F'+D'+C'+H')/4×w', the rank correlation method is used, and the results are : a) In some species, there is a great discrepancy between the dominance indicated by(F'+D'+C')/3×w' and that indicated by(F'+D'+C'+H')/4×w'. Ryegrass is one of these examples, but in case of clover, there is scarcely no difference between the two. b) Comparing the dominances indicated by(F'+D'+C')/3×w', and (F'+D'+C'+H')/4×w' with the yield of grass, there is a close relationship between the yield and(F'+D'+C'+H')/4×w'. It seems that (F'+D'+C')/3×w' is an ecological amount more than (F'+D'+C'+H')/4×w'.