A sheet of colloidal crystals immobilized in resin exhibiting intense structural color and allowing easy observation thereof from squarely facing direction against the surface; and application thereof are provided. The sheet includes crystal domains comprising colloidal crystals immobilized in resin. The Bragg reflection intensity resulting from crystal domains according to back reflection spectrum measurement to the sheet surface satisfies the following conditions (1) and (2). (1) When elevation angle from the sheet surface is in a range of at least 60° and less than 90° and measurement is performed at a predetermined azimuth angle on the sheet surface, intensity is not 0 and (2) when elevation angle from the sheet surface is in the range of at least 60° and less than 90° and azimuth dependency on the sheet surface is measured, the intensity exhibits a maximum value at the the predetermined azimuth angle.
