Lactophoricin (LPcin), which is a part of proteose peptone isolated from bovine milk, is a cationic amphipathic α-helical antimicrobial peptide. Its truncated variants and mutated analogs were designed and their antimicrobial activities were evaluated by using various assays, like broth dilution methods and disk diffusion methods as well as hemolysis assay. Three analogs, LPcin-C8 (LPcin-YK1), LPcin-T2&6W (LPcin-YK2), and LPcin-T2&6W-C8 (LPcin-YK3), which showed better antibiotic activities than LPcin, were selected. Their secondary structures were also characterized by using CD spectropolarimetry. These three analogs of LPcin could be used as an alternative source of powerful antibacterial agents.