From the view point of MgO for radiation detector uses, in the 1970s, undoped MgO powder was found to show dosimeter properties. When it was irradiated by X-ray, γ-ray and UV, two TSL glow peaks were found around 90-100 and 140 °C [1]. Furthermore, in the later decades, MgO have been intensively studied for dosimeter applications due to the bioequivalency [2]. In this study, we synthesized a series of transparent ceramic MgO doped with 0.001, 0.01 and 0.1% of C by a Spark Plasma Sintering (SPS) method and studied scintillation and dosimeter properties against X-rays. The C-doping is inspired by C-doped Al2O3crystalline powder used for a personal dosimeter [3]. Recently, it was pointed out that scintillation and dosimeter are complementarily related in some material systems [4] so investigations of both the dosimeter and scintillation properties are important to understand the luminescence phenomena induced by ionizing radiations. In the scintillation spectra, the emission bands were detected around 400 and 760 nm, and the origins of these peaks were assigned in previous reports [5]; therefore, we think that emission peaks around 400 and 760 nm may be due to F+ center and Cr3+ ion impurity, respectively. Moreover, the emission peak was also observed at 330 nm and it is said that its origin related to surface (grain boundary) defect [6]. Compared with the scintillation spectrum of the undoped MgO transparent ceramic in Ref [5], 330 and 400 nm peak intensities increased while 750 nm peak intensity decreased with C-doping. This result suggests two possibilities; a first one is that electrons are hard to transport to Cr3+ ion because C-doping generated F+ center and surface defect acting as emission center newly. The number of generated careers are finite, and if most careers recombine at these defect emission centers, Cr3+emission should be reduced. A second one is that defects generated by C-doping simply act as trapping centers, and in this case, careers would be stored. H. Nanto, K. Inabe, H. Yamazaki and N. Takeuchi, J. Phys. Chem. Solid., 36 477 (1975). C. Soliman, Radiat. Eff. Defect. S., 164 257 (2009). S.W.S. McKeever, Radiat. Meas., 46 1336 (2011). T. Yanagida, J. Lumin., 169 544 (2016). T. Kato, G. Okada, T. Yanagida, Ceram. Int., 42 5617 (2016). F. Gu, et al., J. Alloy. Compd., 453 361 (2008)