PROBLEM TO BE SOLVED: To provide a thin paper that is good in strength properties and excellent in liquid permeability.SOLUTION: Thin paper is mainly composed of an aggregate of two hydrophilic cellulose fibers having different fiber roughness and contains a paper-strengthening agent. As the two hydrophilic cellulose fibers, a first pulp having a fiber roughness of 0.13-0.16 mg/m and a second pulp having a fiber roughness of 0.17-0.20 mg/m are contained, and the difference of the fiber roughness between the contained first pulp and the contained second pulp is 0.01-0.07 mg/m. The aggregate has a freeness of 400-550 ml.
