Abstract: The aggregation and phase separation of inorganic particles are performed in a sol containing the inorganic particles and a solvent to produce a porous body having open pores. Preferably, the inorganic particles are particles of one or more inorganic material selected from the group consisting of titania, silica, alumina, zinc oxide and zirconia. Further, the sol may have strong acidity and the pH of the sol is elevated to perform the aggregation and phase separation of the inorganic particles. Alternatively, the sol may have strong basicity and the pH of the sol is lowered to perform the aggregation and phase separation of the inorganic particles. The present invention provides a novel method of producing a porous body and sintered body having co-continuous structure, applicable to a wide variety of inorganic materials.