Monodispersed mesoporous silica spheres (MMSSs) are silica colloid particles with uniform mesopores and particle diameters. MMSS ionic colloidal crystals can be fabricated by self-organization and immobilization using a hydrogel. From measurements of the emission light of the gel-immobilized MMSSs where a laser dye was incorporated, laser emission occurred through the excitation by a YAG laser.