Twenty hexamethine (streptovinyl or part of them were composed of isophoron) hemicyanine dyes (I and III), containing benzothiazole nucleus and various amines were synthesized. Two symmetrical heptametine (straight chain or isophoron) thiacyanine dyes (II and IV) and ten pentamethine intermediate dyes (V) containing various amines both ends of them were also synthesized. There were found the linear relationship between the absorption max. of hemicyanine dyes and basicity of the amine as a composition of them, when the amine's basicity values lay within the range of pKa : 3.92 up to 5.61. And above pKa : 8.36 up to 11.12, there were found abnormality in these hemicyanine dyes. There exist only a few deviation between the observed absorption max. of (I) dyes and the mean value of the max. of the pair of related symmetrical dyes (V) and (II). Silver iodo-bromide emulsions were sensitized with these dyes which were much effective sensitizer, and lack of sensitivity at green region of spectrum were observed in every cases. Sensitization spectra for silver iodo-bromide emulsion with seven dyes were illustrated together with a control.