As a novel method improving the safety of conventional oral ivermectin (IVM) for scabies treatment, we conceived an idea called the “whole-body bathing method”. In this method, the patients would bathe themselves in a bathing fluid containing IVM at an effective concentration. To evaluate the feasibility of the method, we investigated the IVM concentration in the skin and plasma after bathing rats in a fluid containing 100 ng/mL of IVM. After the bathing, the concentration of IVM in the skin was more than 400 ng/g wet weight and was maintained until 8 h after the bathing. The concentration was clearly higher than that in patients taking IVM p.o. as previously reported; IVM was not detected in plasma in the present study. Thus, the method would be a preferable drug delivery system for the skin application of IVM compared with p.o. administration.