There is disclosed a method of manufacturing a porous body, which is capable of preferably manufacturing the porous body having a high open porosity and a small thermal expansion coefficient. In the manufacturing method, a raw material including an aluminum source and a titanium source is fired to obtain the porous body containing aluminum titanate as a main component. In this manufacturing method, inorganic micro balloons containing an aluminum component and/or a silicon component are used as a pore former.