In this study, the backs with a hair cut of 6-week-old healthy ICR male mice were once exposed to a dose of $400;mJ/cm^2$ UVB. An acute dermal inflammation was observed, and the certified 100% pure and natural lavender essential oil were applied to the UVB-exposed mice skin twice a day. It was observed that the mice exposed to UVB resulted in an acute inflammation, and when treated with lavender oil the degree of inflammation was much alleviated, and the inflamed skins of both the control and lavender oil-treatment groups were cured almost completely after 6 days of the UVB exposure. At 24 hours after UVB exposure, the epidermal keratinocytes in the control group showed a cell-membrane damage with the destruction of intercellular junctions, agglutination of tonofilaments within the cytoplasm and nucleus damage, while the lavender oil-treatment group had much less cell damage than the control group. While the control group showed a significant increase (p<0.05) in the activity of XO up to 144 hours, the lavender oil-treatment group did not show any significant increase except for 48 hours after the UVB exposure. Both the control and lavender essential oil-treatment groups had a significant decrease in the activities of CAT and SOD up to 96 hours. Particularly, the CAT activity was significantly lower(p<0.05) in the lavender oil-treatment group than the control group up to 48 hours, and higher than the control group at and after 96 hours. The GST activity was significantly decreased in both the control and lavender oil-treatment groups up to 96 hours after the UVB exposure except for the control group at 24 hours, and that of the lavender oil-treatment group was higher than the control group at and after 96 hours. Therefore, it is assumed that the application of the lavender oil to the ultraviolet-damaged mice skin can be effective in treatment for the damaged skin.