The present invention relates to a thermal insulator using closed cell expanded perlite. The thermal insulator using closed cell expanded perlite of the present invention includes: expanded perlite 10 to 84 wt %ç, including dried and expanded perlite ore particles, having a surface with a closed cell shape, as an active ingredient; a liquid binder 15 to 85 wt %; and a reinforcing fiber 0.25 to 5 wt %. Accordingly, the present invention provides a thermal insulator, which enhances the rigidity of expanded perlite, minimizes porosity and gaps between the expanded perlite particles, by reducing compression ratio during compression molding, which results in lower density, improves constructability by lowering thermal conductivity, reduces material and energy costs and can reduce the area required for equipment installation by reducing the thickness of the thermal insulator.