To dry at a low cost in a short time, while processing a gelatinizing, lumping or sticking phenomenon characteristic of a food waste occurring in vacuum drying to be conducted, while heating industrial waste containing a moisture or particularly food waste.

A dryer comprises a fixed blade 15, having downwardly fixed cutting blades 16 group, a water flow ejector having agitating blades 17a which have scraping blades under the blades 16 and agitating blades 17b, having upward and downward rotary cutting blades 19 group mounted on a rotary shaft 6 to vacuum dry a waste in a dry tank 2, and a burner 1 for heating the tank in a dry tank 2. Gelatinizing, lumping of the waste and sticking to an inner wall of the tank by the scraping blade are prevented, by fixed cutting blades group and the upward and downward rotary cutting blades, and the waste is dried at a low cost, in a short time.