The inhomogeneous character of structural relaxation in Zr-based bulk metallic glass (BMG) was investigated from both aspects of the fine structure of free volume, i.e. like the identification of n-, p-type defects, and the chemical short-range order (CSRO) induced by thermal treatment. At least within volume relaxation used in the present study the fine structure of free volume could not be detected. On the other hand, the CSRO process was confirmed to take place in a Zr₅₀Cu₄₀Al₁₀ BMG by electrical resistance experiments. Although the fine structure of free volume could not be observed in the present glass, the existence of the CSRO process suggests any structural inhomegeneity in BMGs.