GATA-2 is a transcription factor expressed in stem and progenitor cells of various cell lineages. In this study, we examined the role of GATA-2 in the differentiation of adipocytes, which are the main components of the microenvironment for hematopoiesis. Suppression of GATA-2 in TBR343, a preadipocytic stromal cell line, resulted in the acceleration of adipocyte differentiation. Conversely, overexpression of GATA-2 induced the resistance of adipocyte differentiation. In addition, regulatory elements of the GATA-2 gene in TBR343 are the same as those in hematopoietic cells. These results suggest that GATA-2 maintains a hematopoietic microenvironment by regulating the differentiation of adipocytes.