Provided is a novel bacteriophage ΦCJ21 (KCCM11363P). In addition, the present invention relates to an antibacterial composition including the bacteriophage ΦCJ21 (KCCM11363P) as an active ingredient. Further, provided is a method of preventing and/or treating infectious diseases by Clostridium perfringens in animals except for humans using the bacteriophage ΦCJ21 (KCCM11363P) or the antibacterial composition containing the bacteriophage ΦCJ21 (KCCM11363P) as an active ingredient.