SmFe4P12 is a novel ferromagnetic heavy fermion compound with a Curie temperature Tc of 1.6K. The electronic specific heat coefficient is 370 mJ/mol·K2. The magnetic susceptibility of La1-xSmxFe4P12 (0.6 ≤ x ≤ 0.85) with a paramagnetic ground state shows a broad maximum around 15K. This phenomenon reminds us the case of CeRu2Si 2 which is in the boundary of itinerant and localized 4f-state. We measured the magnetization up to 42T and found metamagnetic crossover at 22T. The metamagnetism disappears with increasing temperature. Possible mechanism of the metamagnetism is discussed. ©2008 The Physical Society of Japan.