PURPOSE: To improve flowability by mixing a hydraulic material, water, a fine aggregate, a coarse aggregate and a cement dispersing agent consisting of an alkenyl ether/maleic anhydride copolymer expressed by a specific formula in a prescribed weight ratio.

CONSTITUTION: The cement dispersing agent is obtained by mixing the alkenyl ether/maleic anhydride copolymers, the hydrolyzed materials or the salt expressed by formula (a), R1O(AO)mR2, and formula (b), R1O(AO)nR2 (AO represents a 2-18C oxyalkylene, R1 represents a 2-5C alkenyl, R2 represents a 1-4C alkyl and each of (m) and (n) represents average addition numbers of oxyalkylene respectively of 1-40 and 100-150) in a weight ratio of component (a)/component (b)=(97-59)/(3-50). Next, a high flowable concrete composition consisting of 350-700 kg hydraulic material as a unit weight in 1 m3 concrete, ≤180 kg water as a unit weight in 1 m3 concrete, an adequate quantity of the fine aggregate and the coarse aggregate and 0.05-3 pts.wt. cement dispersing agent per 100 pts.wt. hydraulic material is obtained by kneading the dispersing agent with the cement materials.