Handwashing is critically important in preventing infection as it prevents pathogens on your hands from entering your body through your mouth or eyes. In this study, we examined the persistence of the antibacterial effect after handwashing with a hand soap formulation containing fatty acid salts and poly diallyldimethylammonium chloride（PDADMAC）on human skin. To achieve the persistence of this effect, we utilized the coacervation technology, which involves complex precipitation due to the interaction between anionic surfactants（fatty acid salts）and cationic polymers（PDADMAC）, caused by dilution during the washing process. The results of the persistence of the antibacterial effect on human skin against E. coli and S. aureus showed significantly higher efficacy even 4 h after handwashing compared to handwashing without hand soap, suggesting that the use of this formulation in handwashing may provide the persistence of antibacterial effect on the hands. In addition, when the results of the persistence of the antibacterial effect and the residual components on human skin were compared with those on model skin, similar trends were observed in both cases. This indicates that the evaluation using model skin can effectively predict the results on human skin. The findings of this study contribute to reducing the risk of contact infection after handwashing.