In order to evaluate the efficacy and safety of Mentholatum^ò AP Soft Lotion (APA), which is a Vaseline-based preparation that has been converted to nanoparticles by high-pressure emulsification technology, we conducted a study of 4-week continuous use on the atopic dry skin of patients with minor to moderate atopic dermatitis (AD). The results showed that improvements in the skin findings (dryness and scaling) and itching were observed beginning one week after starting to apply APA and that the symptoms had almost completely resolved at 3 to 4 weeks after the start of application. In addition, a significant increase in the degree of high-frequency conductivity, which is an indicator of the amount of moisture in the stratum corneum, and significant decrease in transepidermal water loss (TEWL) were observed, and improvements in skin functions were observed. The results for overall degree of improvement showed “improvement” or better in 100% of the subjects, and no side effects were observed in any of the cases. Based on the above results, it was concluded that APA is a preparation that has excellent efficacy and safety as skin care for atopic dry skin, in which reduced stratum corneum function is observed in the skin, and as a supplemental method of treatment of AD or treatment method to maintain remissions.