A process for production of a mesoporous structure wherein fine particles having a mean particle size smaller than the size of pores of a mesoporous body formed using a template are formed in the pores of the mesoporous body. The process comprises the steps of: preparing an aqueous solution comprising a mixture of the template and the fine particles, heating and pressurizing the aqueous solution to bring the water in the aqueous solution to a subcritical water state, returning the aqueous solution to a state at a room temperature and under atmospheric pressure, dissolving the starting material of the mesoporous body in the aqueous solution and heating it to form a precipitate comprising the template, fine particles and starting material of the mesoporous body, and separating, drying and firing the precipitate to burn off the template from the precipitate.