The colossal magnetoresistive material, La0.7Ca0.3MnO3, which has the perovskite structure, has been investigated by means of a magneto-optical method. Analysis of the magnetic field distributions within such a material under applied perpendicular fields clearly showed that the sample was paramagnetic above the Curie transition temperature Tc and ferromagnetic below it. The field distributions were also studied as a function of decreasing temperature through Tc. The results show the microscopic magnetic transition process as the material changes magnetic phase. © 1999 American Institute of Physics.