  We present a formula for tunneling conductance in ballistic
ferromagnet/ferromagnetic insulator/superconductor junctions where the
superconducting state has opposite spin pairing symmetry. The formula can
involve correctly a ferromagnetism has been induced by effective mass
difference between up- and down-spin electrons. Then, this effective mass
mismatch ferromagnet and standard Stoner ferromagnet have been employed in this
paper. As an application of the formulation, we have studied the tunneling
effect for junctions including spin-triplet p-wave superconductor. The
conductace spectra show a clear difference between two ferromagnets depending
upon the way of normalization of the conductance. Especially, a essential
difference is seen in zero-bias conductance peaks reflecting characteristics of
each ferromagnets. From obtained results, it will be suggested that the
measurements of the tunneling conductance in the junction provide us a useful
information about the mechanism of itinerant ferromagnetism in metal.
