The present invention provides a multicolor display optical composition comprising a dispersion medium, a periodic structure having a porous structure inside communicated with the outside, and mobile particles contained in the dispersion medium so as to be movable and having a volume average primary particle diameter from 1 nm to 80 nm in a dispersion state in the dispersion medium, a volume average particle diameter of coagulated particles of 100 nm or larger in optical coagulation state by stimulation application, and having a refractive index different from that of the dispersion medium by 0.1 or more, wherein the mobile particles show no coloration in the dispersion state when the particles are dispersed in the dispersion medium and show white coloration with a predetermined whiteness value or higher in the coagulation state when the particles are coagulated, an optical device, and a display method of the optical device.