PURPOSE: To provide a dehydrator slidably equipped with a press device at the lower portion of a hopper with a cutter member arranged at the lower side thereby accomplishing accurate dehydration of large amount of screen cake or the like.

CONSTITUTION: Screen cake or the like is fed into a inner hole of a outer press into upper and lower guide plates 2 and 3 from a hopper 1 is dehydrated under pressure with an inner press advancing by a dehydrating cylinder 8. Then, as maintained under the pressure, the whole of the inner andouter press is slided toward delivery port. Released from the pressure, the cake dehydrated is let drop