We have reported that Eucommia leaf extract (ELE) influences the early stage of differentiation of both osteoblast and chondrocyte cells. Therefore, in this study, we focused on the bone marrow containing mesenchymal stem cells, which are the origin of both cells, and analyzed protein composition in bone marrow of rat administered with ELE. Femoral bones were extirpated from 2-month-old wistar rats orally administered with 10% ELE for 3 days. Bone marrow was washed out from the diaphysis of femur by lysis buffer and protein was extracted from the obtained bone marrow and fluorescent labeling was performed. Protein separation was then carried out by the immobilized pH gradient method. Subsequently, protein separation was carried out by molecular weight by performing SDS-PAGE. After electrophoresis, a fluorescence image of the gel was captured and image analysis was performed using ImageMsater 2D Platinum 7.0. Proteins were then extracted from significantly changed spots and mass spectrometry was performed by MALDI-TOF-MS. As a result of image analysis, 1,567 spots changed in expression level, and 74 spots were detected in which protein amount was changed more than 2 times. In addition, 20 spots were detected in which the expression was changed at 0.05> P.