Plasma temperature decreases due to the micro turbulence in nuclear fusion plasmas. In order to control this turbulence, detailed investigation to understand the physical mechanism of the turbulence is necessary. It is known that the intensity of visible light emitted from plasmas is proportional to the plasma density. We will launch the “Beam Emission Spectroscopy Instrument,” which can obtain the information of turbulence and plasma density. As a first step, we will conduct a characterization of the spectrometer.