A thermal insulator with both excellent heat insulation and strength and a method of manufacturing the thermal insulator are provided.A thermal insulator according to the present invention includes metal oxide fine particles with an average particle diameter equal to or smaller than 50 nm and a reinforcing fiber, wherein the thermal insulator has a bridge structure between the metal oxide fine particles which is formed by elution of part of the metal oxide fine particles. A method of manufacturing a thermal insulator according to the present invention includes a curing step of curing a dry pressed compact including metal oxide fine particles with an average particle diameter equal to or smaller than 50 nm and a reinforcing fiber under a pressurized vapor saturated atmosphere at a temperature equal to or higher than 100° C. for four hours and a drying step of drying the cured dry pressed compact.