Provided is a mesoporous particle having a flaky shape, having a single-layer structure, having a thickness of 0.1 μm to 3 μm, and having an average pore diameter of 10 nm or more. The mesoporous particle can be obtained by a production method including: feeding a metal oxide sol having a pH of 7 or higher and containing metal oxide colloidal particles as dispersoids and water as a dispersion medium, into a liquid containing a water-miscible solvent having a relative permittivity of 30 or lower (protic solvent) or of 40 or lower (aprotic solvent) at 20° C., and thereby forming a flaky aggregate of the metal oxide colloidal particles in the liquid; and subjecting the aggregate to treatment such as drying and heating, and thereby converting the aggregate into a flaky particle that is insoluble in water.