Bacillus cereus causes food poisoning, resulting in vomiting and diarrhea, due to production of enterotoxins. As a means of controlling this food-borne pathogen, the virulent bacteriophage B4 was isolated and characterized. Bacterial challenge assays showed that phage B4 effectively inhibited growth of members of the B. cereus group as well as B. subtilis, and growth inhibition persisted for over 20 h. One-step growth analysis also revealed the host lysis activity of phage B4, with relatively short eclipse/latent times (10/15 min) and a large burst size (>200 PFU). The complete genome of phage B4, containing a 162-kb DNA with 277 ORFs, was analyzed. The endolysin encoded by the phage B4 genome accounts for the cell lysis activity of this phage. These results suggest that phage B4 has potential as a biological agent to control B. cereus propagation.