A halogen treatment is conducted comprising: a halogenation step wherein a halogenation heat treatment for preparing a halogenated carbonized charcoal is conducted in which the carbonized charcoal is brought into contact with halogen; and a dehalogenation step wherein a dehalogenation treatment is conducted in which a part of or all halogen atoms in the halogenated carbonized charcoal are eliminated. A porous carbonaceous material is obtained at a high yield, and the amounts of nitrogen, oxygen, carbon dioxide, and methane adsorbed by this porous carbonaceous material are large. When this porous carbonaceous material is used as an electrical double layer capacitor carbon, the electrostatic capacity is increased compared to conventional carbonaceous materials. Consequently, a carbonaceous material is obtained which has micopores and/or sub-micropores which are suitable for the adsorption of small molecules such as nitrogen, and for storage of electrochemical energy.