A novel porous fibrous structure containing from 10 to 100% by weight of wet heat bonding fibers, having cellular cavities in the fibrous structure of the fibers, in which a plurality of indefinite cellular cavities are present independently or in a state of partially connected in the inside of the fibrous structure, at least a portion of the fibers constituting the fibrous structure is heat bonding by the wet heat bonding fibers, and a process for producing such porous fibrous structure.