The cement composition for extrusion molding including 100 weight parts of a blend comprising a hydraulic material, an aggregate and a fiber; 0.1 to 1.5 weight parts of an extrusion aid, 15 to 45 weight parts of water and 0.01 to 2.0 weight parts of a copolymer. The copolymer includes 50 to 99 weight percents of an unit (a) derived from a polyoxyalkylene derivative represented by the formula (1), 1 to 50 weight percents of an unit (b) derived from maleic anhydride or a dicarboxylic acid represented by the following formula (2) and 0 to 30 weight percents of an unit (c) derived from an additional and copolymerizable monomer.