The present invention provides a ceramic foam, comprising: a ceramic slurry prepared by mixing a foam with micro cells or bubbles obtained by a foaming agent diluted in water, silicate, ceramic powder, and additives; and a gelling agent supplied to the ceramic slurry to form a 3D-silica network while maintaining the shape of the ceramic slurry. The ceramic foam is manufactured by diluting a foaming agent in water; forming a large number of closed cells by using a foam system having the water-diluted foaming agent; mixing the obtained foam with silicate, ceramic powder, and additives to form a ceramic slurry; supplying a gelling agent to the ceramic slurry to form a 3D-silica network while maintaining the shape of the ceramic slurry; and drying the ceramic slurry to remove moisture inside, and fusing additives thereon to improve water resistance.