Herein we demonstrated irradiation of electron beam with various dose levels to improve reactivity of MnOx/CNFs. For fabricating MnOx/CNFs, DMF solutions of PAN(7 wt. %) containing different amount of Mn(OAc)2 (0, 6, 12, 18, and 24 wt. % to PAN) were used as polymer resin for electrospinning. The collected nanofibers were firstly stabilized in air at 300 oC for 4 hrs (ramping rate: 2 oC/min), and then carbonized at 850 oC for 2 hrs (ramping rate: 3 oC/min) in Ar to achieve MnOx/CNF products. After then showing the highest results mats were subjected to electron beam (e-beam) irradiation using a high-energy electron accelerator. E-beam was generated using a 0.2 MeV acceleration voltage, a 0.5 mA current and a 0, 500, 1,000, 2,000, 3,000 and 5,000 kGy absorbed dose, respectively. The influence of Mn(OAc)2 content on CNFs was investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, X-ray photoelectron spectroscopy(XPS), Raman spectroscopy and cyclic voltammetry (CV). From the results, exceptional performance ensures to have potential for supercapcitor of manganese oxide composite nanofibers. In addition, these results have verified the effect of electron beam to improve capacitive performance of MnOx/CNFs. Acknowledgement This work was supported by National Research Foundation of Korea (grant no.: 2013M2B2A4041305 and 2013R1A2A2A04013913). Keywords: electrospinning, manganese oxide, nanofiber, supercapacitor.