The typical perovskite manganite (La,Pr,Ca)MnO3 shows exotic colossal magnetoresistivity which is associated to the insulator-metal transition (IMT)  from an insulator behavior at a high temperature to a metallic behavior at a low temperature through a critical transition temperature TIM. Around TIM, the phase-separated metal and insulator domains coexist in a nanometer scale. Since the conductive property in a phase-separated material is determined by the conductivity behaviors of metal/insulator nanodomains, understanding the electrical transport properties, i.e., quantitative evaluation of the change of metal fraction (X(T)) and the dc conductivity (σdc(T)) are required. Interestingly, owing to the confinement of nanodomains, the peculiar property was observed in a nanostructure , therefore the investigation of their electrical transport properties becomes extremely important. However this is still a challenging issue by using the electrical measurement with attached electrodes.