To provide a rapid dehydrator composed of a new structure, in which crushed stones and aggregate, on which a large amount of moisture are carried by a washing or the like, can be dehydrated quickly, and a new quick dehydrating method for the aggregate using it.

In the rapid dehydrator 1 for the aggregate, a rotary separating tank 2, which is formed in a truncated cone-shaped cylindrical body having a comparatively long body and being used as a water-passing peripheral wall 23 and a discharge opening section 21 is formed on the large diametral end side and a journalizing wall section 22 on the small diametral end side while rotating blades 24 are projected from the internal surface of the wall 23 in an inward uniform arrangement, is arranged on a horizontal axial center, and then a radial drive mechanism rotatable in the peripheral direction R is installed while a thrust drive mechanism in a manner that the thrust drive mechanism can be reciprocated in the axial-center direction S is mounted, and a slurry guide pipe 3 being introduced from the discharge opening section 21 and guiding slurry near the wall section 22 close to the shaft is secured.