PURPOSE: To obtain sintered substrate for battery where porosity is increased uniformly by depositing, to the conductive core body, the slurry obtained by mixing the resin consisting of fine hollow sphetic bodies internally comprising a foaming substance, Ni powder, water and viscosity increasing agent and by sintering such mixture.

CONSTITUTION: A foaming agent, which internally comprises a substance which foams when heated in a fine hollow spheric material made of resin, is formed. This foaming agent is mixed with Ni powder and viscosity increasing agent and is then stirred to form the slurry. The slurry is deposited, dried up and then sintered at the specified temperature. Thereby, porosity can be uniformly increased without increase of manufacturing steps. Moreover, the porous sintered substrate having high capacity of active substance filled and high mechanical strength can be obtained.