The present invention relates to a novel bacteriophage having an E. coli-specific bactericidal activity, a composition for the prevention or treatment of infectious diseases caused by Enterotoxigenic E. coli comprising the bacteriophage as an active ingredient, an antibiotic comprising the bacteriophage as an active ingredient, a feed additive composition comprising the bacteriophage as an active ingredient, a sanitizer or cleaner comprising the bacteriophage as an active ingredient, and a method for treating colibacillosis using the bacteriophage. The novel bacteriophage of the present invention has a specific bactericidal activity against pathogenic E. coli, and excellent acid- and heat-resistance. Therefore, the novel bacteriophage can be used for the prevention or treatment of swine colibacillosis, which is an infectious disease caused by pathogenic E. coli, and can also be widely used in animal feed additive compositions, sanitizers, and cleaners.