For the development new cephalosporin antibiotics with aminothiazolmethoxyimino moiety in the C-7 position and triazolthiomethyl moiety in the C-3 position of cephem ring, $7{eta}$-[(z)-2-(2-aminothiasol-4-yl)-2-(methoxyimino)acetamido]-3-[5-(aryl or het.)-4-phenyl-4H-1,2,4-triazol-3-yl]thiomethyl-3-cephem-4-carboxylic acids were synthesized. These compounds were tested for antimicrobial activitiy in vitro against ten species of microorganisms. It showed remarkable antibacterial activity against Bacillus subtilis ATCC 6633, Micrococcus luteus ATCC 9341 and Escherichia coli ESS. The antibacterial activity of most new compounds showed more active than cefazoline, but these compounds were lower active than cefotaxime against Pseudomonas aeruginosa IFO 13130.