A newly identified virulent phage (named phiAS4) infecting Aeromonas salmonicida subsp. salmonicida was isolated from river water in Korea. Morphological analysis of phiAS4 by transmission electron microscopy revealed that it belonged to the family Myoviridae. The genome of phiAS4 comprised a linear double-stranded DNA of 163,875 bp with a G + C content of 41.3%, and genomic analysis revealed 271 putative ORFs, 67 putative promoters, 25 putative terminator regions, and 16 tRNA-encoding genes. Most of the ORFs of phiAS4 showed a high degree of similarity to those of Aeromonas phage 25, which belongs to the T4-like group. Moreover, the comparison of the genome of phiAS4 with those of its relatives demonstrated that phage phiAS4 is closely related to members of the T4-like group and can be classified as a new member of the T4-like phages infecting bacteria of the family Aeromonadaceae.