Adipogenesis is a primary energy valancing response in physiological status and critical in embryo development. One of the essential factors for initiation and maintaining of adipogenesis is the composition of extracellular matrix. Previously, we confirmed the effects of diphlorethohydroxycarmalol (DPHC), an extract of Ishige okamurae, on the antiobesity effects and ECM stability in adipose tissue. In vitro model for adipogenesis study, 3T3-L1, a precursor cell type of adipocyte, and the adipose-tissue derived stem cell (ADSC) can be used. Usually the induction period for adipocyte is shorter in 3T3-L1 than in ADSCs. However, so far, the difference of the expression patterns of ECM components in 3T3-L1 and ADSCs, and the effects of DPHC are not much known. We induced differentiation of 3T3-L1 and ADSCs into adipocyte with or without DPHC (0, 0.4, 2, 10, 50 μg/mL) and confirmed the adipogenesis with adipogenic markers (PPAR-γ, LDL). After then, the levels of collagen type 1 alpha 1 (Col1a1), collagen type 3 alpha 1 (Col3a1), collagen type 4 (Col4), collagen type 6 (Col6), Elastin (Eln) and microfibrillar associated protein 5 (Mfap5) were analyzed with real-time RT-PCR. During early adipogenesis of ADSC, the expression levels of Col1, Col3, Col6, and Mfap5 mRNA were decreased but Col4 and Eln mRNA were increased. In the matured adipocyte, the expression levels of Col1, Col3, Col4, Mfap5 mRNA were decreased but not Eln. In the case of early differentiation of 3T3-L1, the expression levels of Col1, Col3, Eln mRNA were decreased but the expression levels of Col6 and Mfap5 were increased. In matured adipocyte of 3T3-L1, the expression levels of Col1, Col3, Eln, Mfap5 mRNA were increase but the expression level of Col6 mRNA was decreased. The expression levels of Col4, Eln mRNA were suppressed by 50 mg/mL DPHC treatment during early adipogenic period of ADSC. On the other hand in 3T3-L1, the expression levels of Col3 and Col6 mRNA were not changed by the DPHC treatment during early induction period. In the matured adipocytes derived from ADSC, Col1 mRNA levels was not decreased by the treatment of 50 mg/mL DPHC. Col4 mRNA levels was not increased by DPHC treatment. In the case of matured adipocytes derived from 3T3-L1, DPHC suppressed the increase of Col1, Col3, Col6 mRNA expression and the expression of Col4 and Eln mRNA was decreased. In summary, these data show that expression levels of each ECM component types are dramatically changed with some common patterns in two cell types, and the treatment of DPHC can modify the expression patterns of some ECM components in each cell types. It is suggested that one of the reason of antiadipogenic effect of DPHC may be the ECM modification.