  We study an SO(5) model unifying p-wave superconductivity and ferromagnetism.
If only a single p-wave pairing wavefunction is involved, the p-wave
superconducting (pSC) and ferromagnetic (F) states can be unified to form
10-dimensional multiplet of SO(5). The collective modes in pSC and F states are
studied from this viewpoint in terms of a non-linear sigma model.
