We studied to investigate the erythema reduction effects generated by Gagam-Jawoonaek(GJ) application(appl.) after UV exposure. Twenty women in their twenties to fifties with no skin diseases were recruited. We exposed UV as a 6 subsites on the left upper arm of subjects using multi-port solar simulator. After setting Gagam-Jawoonaek(GJ) application(appl.) subsites and non-appl. subsites, we measured erythema degrees(a* values) of the subsites using spectrophotometer. We measured a* values four times(before UV exposure, before application of GJ, twenty-four and forty-eight hours after first application of GJ). We analyzed data using student’s t-test. After UV exposure, a* values on the left upper arm increased. Twenty-four hours after first GJ treat., the changes of a* value on GJ treat. subsites(1.22 ± 0.13 AU) were bigger than GJ non-treat. subsites(1.04 ± 0.12 AU), but there was no statistically significance. Forty-eight hours after first GJ treat., the changes of a* value on GJ treat. subsites(1.95 ± 0.11 AU) were bigger than GJ non-treat. subsites(1.58 ± 0.13 AU), a statistically significance. Gagam-Jawoonaek could decrease erythema by UV exposure.