The bacteriostatic action of trichlorophenoxy alkylene ammonium derivatives, 2(2,4,5-trichlorophenoxy) ethylene N-triethyl ammonium bromide; (2,4,5-TETB), 2(2,4,6-trichlorophenoxy) ethylene N-triethyl ammonium bromide; (2,4,6-TETB), 2,4,5-triphenoxy ethylene pyridinium bromide; (2,4,5-TEPB), and 2,4,6-trichlorophenoxy ethylene pyridinium bromide:(2,4,6-TEPB) were observed by Jackson and Finland's and Finland's and Pak's on Staphylococcus aureus, E. coli, Salmonella typhi, Shigella flexneri, and Bacillus subtilis, comparing with those of phenol and trichlorophenol. The following results were obtained. 1) Phenol is bacteriostatic in a concentration of $10^{-3}$ for all above species. 2) Trichlorophenol is bacteriostatic in concentration of $10^{-4}$ to $5{\times}10^{-5}$ for all above species(Table 7), 3) 2,4,5-TETB and 2,4,6-TETB are bacteriostatic in a concentration of $10^{-4}$ and $5{\times}10^{-5}$ for Staphylococcus aureus, Salmonella typhi, and Shigella flexneri, but do not for E. coli and Bacillus subtilis(Table 8 and 9). 4) 2,4,5-TEPB and 2,4,6-TEPB are bacteriostatic in a concentrationof $10^{-4}$ and $5{\times}10^{-5}$ only for Staphylococcus aureus among four species(Table 10 and 11).