High enthalpy argon gas how was made by an are-heated wind tunnel to analyze physical phenomena around a blunt body. The how fields with and without an axisymmetric blunt body were studied by a spectroscopic approach Number density of excited argon was measured spatially. It is found that the highest number density of excited argon atom was obtained at the stagnation point at the body, which was 2.4 times as high as the uniform flow without body for the atom with 4p＇ [1/2] level. Furthermore, it was confirmed that the dark region exists just in front of the shock wave, where self-luminosity of the high enthalpy how is reduced. In the region called ＇＇dark space＇＇, the number density of atom with higher energy level 4d and 5p was found to relatively decrease compared with that of lower level 4p＇.