Aruncus dioicus var. kamtschaticus HARA, also known as goat's beard, is a native plant in Ulleung-do, South Korea. It has been used as a remedy in skin care, detoxification, blood stanching, tonsillitis. High performance liquid chromatography with diode array detection was used for partial validation of bioactive chemicals in A. dioicus ethyl acetate (EtOAc) extract, and EtOAC extract was examined for its effect on ultraviolet (UV)-induced cell aging using CCD-986sk-human skin fibroblast cells. Cells were exposed to UV-B for 1 min before extract treatment. An established viability assay was performed to test cell toxicity of A. dioicus at 5, 10, or 50 μg/ml concentrations, and activities of matrix metalloproteinase (MMP) 1, 2, 3, phosphorylated-p38 (p-p38, an activated form of p38), p38, and c-fos transcription factors were evaluated. A. dioicus extract decreased the amount of mRNA transcripts and total proteins of MMP1, 2, 3 as well as p-p38 and c-fos. The c-fos expression was also confirmed by in vivo fluorescent staining of CCD-986sk cells after UV-B exposure followed by EtOAc extract treatment. The results showed that expression of skin aging related genes encoding MMP1, 2, and 3 was inhibited by reduced transcription factor expression of p-p38 and c-fos by A. dioicus EtOAc extract. The results suggest that A. dioicus extract can be used to reduce UV-B-induced skin aging and is a potential candidate for cosmedical materials.