Soft magnetic materials need several characteristics to realize high performance. Powder metallurgy is an effective way to produce the complex shaped parts, and also decrease the eddy current loss in high frequency by subdividing the eddy current area due to the small grains. In this study, Metal Injection Molding (MIM) of several types of Fe-6.5Si powders was performed and the magnetic properties were investigated. The relative density of the low oxygen specimens was higher than the others, however, the grain growth that occurred was remarkable. These lower oxygen specimens show good soft magnetic properties, but the iron loss at higher frequencies was increased due to the remarkable grain growth. Both high density and control of grain growth are necessary to obtain the excellent soft magnetic properties.