[en] This thesis describes an investigation on impurity transport in the JT-60U tokamak plasma both in the core and the divertor plasmas to provide a better understanding of plasma physics. This work has been performed under the collaborative graduate school between University of Tsukuba and Naka Fusion Research Establishment of Japan Atomic Energy Research Institute. A radiative divertor experiment with neon gas puff was carried out with an aim of investigating impurity behaviors in the divertor, after the open divertor was modified to the pumped W-shaped divertor. To evaluate neon radiation, analysis was made for lines from neon ions measured with a VUV spectrometer in the divertor plasma. As a result, lines from Ne IV-Ne VIII were identified. By combining the measurement with an absolutely calibrated multi-channel interference filter spectrometer and that with the VUV spectrometer, the radiation loss through neon line emission was estimated in the divertor plasma. In the case of pumping off, the detached plasma evolved into a MARFE. It was observed that the line intensities of highly ionized neon (Ne VII, Ne VIII) increased simultaneously with the formation of the MARFE and furthermore increased after the MARFE formation. It is considered that after the divertor plasma was detached, the plasma flow velocity and the friction force were weaker in the case of pumping off than in the case of pumping on and more impurities moved toward the X-point region. This observation implies reduction of impurity back flow from the divertor to the upstream by the friction force. This thesis indicates that the plasma flow in the SOL (Scrape-Off Layer) is important to confine the impurity in the divertor region and prevent the MARFE for the first time. In reversed shear discharges with ITB (internal transport barrier), electron density, temperature and radiation power strongly increased inside the ITB. The core radiation was analyzed by bolometry, VUV spectrometer and CXRS (charge exchange recombination spectroscopy). The core radiation was evaluated with the spectroscopic method in the reversed shear regime. 97% of the main plasma radiation was Bremsstrahlung and this estimation agreed with the bolometric measurement within 10%. During high performance discharges with reversed shear, the radiation profile strongly peaked inside the ITB radius. The increment of carbon density is explained by neoclassical transport of banana-banana collision regime. However, n_c/n_e is flat inside the ITB radius during the electron density increase implying that the discharge has not reached a steady state. If the impurity keeps accumulating at the center as predicted by neoclassical transport theory, the carbon accumulation may pose a problem to the core plasma performance. (author)