We developed a Monte Carlo method to study the magnetic and transport properties of low density carrier ferromagnetic (FM) semiconductors. The calculation is carried out for the two- and three-dimensional Ising spin system interacting with electrons through the s-d exchange coupling. When the temperature increases from T =0, the spontaneous magnetization of the local spins decreases appreciably in the low T range, and steeply at the Curie temperature ( T C ). The initial decrease is caused by the almost complete escape of electrons from the spin flipped sites, and accumulation in the FM region. The electron spin polarization is complete in the whole FM temperature range except very near T C . The Curie temperature shifts to low T side from the value estimated based on the RKKY model as the exchange constant increases. The critical-scattering-like peak of the resistivity appears near T C when the exchange interaction is not so strong, but it disappears when the interaction is strong. In the former cases, t...