PURPOSE: To obtain a high strength by uniformly dispersing water in cement aggregate by passing powdery cement aggregate composed of a specific material through water sprayed in a mist form in a powdery state to knead the same with water.

CONSTITUTION: A spray apparatus 2 is arranged above the charging port of a mixer 1 kneading cement aggregate A with water B. The spray apparatus 2 is equipped with a plurality of spray parts of water B. The supply apparatus charging the cement aggregate A to the mixer 1 is provided above the spray apparatus 2. The cement aggregate A is constituted of cement and an inorg. filler. The cement aggregate A is allowed to fall to the spray apparatus 2 in a powdery state from the supply apparatus 3 and water is sprayed to the powdery cement aggregate A in a mist form within the spray apparatus 2 to be uniformly dispersed in the powdery cement aggregate A. At this time, water is sprayed in an amount optimum to the kneading of the cement aggregate A. After water is added to the cement aggregate A, the resulting mixture is charged in the mixer to be kneaded.