In general, the salinity of the ocean is close to 3.5％ and marine vibrios possess the respiratory chain-linked Na$^$+/ pump. The influence of sodium chloride and the proton conductor carbonylcyanide m-chlo-rophenylhydrazone (CCCP) on the production of extracellular proteases in a marine Vibrio strain was examined. At the concentration of 0.5 M, sodium chloride minimally inhibited the activity of extra-cellular proteases by approximately 16％, whereas at the same concentration, the producton of extra-cellular proteases was severely inhibited. On the other hand, the production of extracellular proteases was completely inhibited by the addition of 2 ${mu}$M CCCP at pH 8.5, where the respiratory chain-linked Na$^$+/ pump functions.